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Vol. 108 Wathington : 1959 Nc 3410A FURTHER STUDY OF MICRONESIANPOLYCLAD FLATWORMSBy LiBBiE H. Hyman *The material treated in this article was assembled from severalsources: one vial from the Templeton Crocker Expedition of 1933,collected at Vanikoro Island; one vial taken at Guam by D. H. John-son; three vials collected by Cadet Hand at Kapingamarangi Atollin the Caroline Islands; six vials from Eniwetok Atoll collected byD. J. Reish; 21 vials collected on Ifaluk Atoll, western Carolines,under the auspices of the Pacific Science Board Atoll ResearchProgram, 1953, mainly by D. P. Abbott, some by F. M. Bayer andothers; 20 vials collected in the Palau Islands, 1955, by a team com-posed of R. R. Harry, H. A. Fehlmann, and F. M. Bayer, fromStanford University and the U. S. National Museum (USNM) ; andtwo polyclads found in a miscellaneous collection of material from thePalau Islands presented to the American Museum of Natural History(AMNH).The field work at Ifaluk and Kapingamarangi Atolls was supportedby funds from Contract N 7-onr-29104 (NR 388-001) by the Officeof Naval Research, Department of the Navy, and National Academyof Sciences. Work at Palau was undertaken by arrangements withthe Pacific Science Board (National Academy of Sciences?NationalResearch Council) and the Office of Naval Research under ContractN 7-onr-291 (57).The polyclads of the tropical and subtropical waters of the vastIndo-West Pacific region are imperfectly known and have not been
> American Museum of Natural History, New York, N. Y. 543
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systematically collected. Species from this area are widely scatteredin the literature. Articles dealing specifically with Micronesian poly-clads are those of Kato (1943) and Hyman (1955b). Kato listedthree new and fom* known species from the Palau Islands, of whichonly one was recovered in the present material, and Hymantwo new and two known species from Micronesia, of which one hasbeen recovered here. The prevalence of known species in even suchsmall collections indicates a wide distribution of polyclad speciesin the Indo-West Pacific area.Taxonomic categories have been defined in previous publications,especially Hyman (1953a), and definitions will not be repeated here.Only categories not found in previous articles will be explained.Order PoLYCLADiDASuborder AcotyleaSection CraspedommataFamily Latocestidae Laidlaw, 1903Latocestus pacificus Laidlaw, 1903FiGUEE la-eMaterial: One specimen collected by the Stanford team at thePalau Islands, Sta. 64, from a small bay at the south end of the la-goon of Eil Malk, Aug. 7, 1955.General characters: The worm, 11 mm. long and about 1 mm.wide, has the strap shape typical of the genus (fig. la). It is brown,of thick, opaque consistency. The numerous small eyes begin wellposterior to the anterior margin as a median band, irregular at firstbut becoming bilateral in arrangement before reaching the brain;anterior to the brain the eyes spray out over the anterior end as usualin the genus (fig. 16). The marginal eyes are not well delimitedfrom the frontal eyes but continue for a short distance posterior tothe level of the brain. The position of the brain is shown in figure16. Because of the dark, opaque consistency of the worm the exactarrangement of the eyes was difficult to ascertain and, further, littlecould be seen of the internal anatomy. The short ruffled pharynxwith the mouth at its posterior end occurs near the posterior end ofthe worm as typical of the genus, and between the mouth and the pos-terior margin are seen the male and female gonopores (fig. la).CopuLATORY apparatus: The posterior end of the worm was re-moved and sectioned sagittally. The contained copulatory apparatusesare shown in sagittal view in figure Ic and are characteristic of thegenus. The free prostatic vesicle with thick musculai* wall and
POLYCLAD FLATWORMS?HYMAN 545
Figure l.?a-c, Latocestus pacificus: a, dorsal view; b, anterior end, enlarged, showing eyepattern; c, sagittal view of copulatory apparatuses, d-f, Plehnia tropica: d, dorsal view;e, sagittal view of copulatory apparatuses; /, cross section through penis stylet. (Forexplanation of numbered parts see p. 597.)
546 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io8glandular interior is relatively large; it stands almost erect, althoughthis may be partly caused by contraction, and terminates belowin a small, conical penis papilla, which is entered by the ejaculatoryduct formed from in front by the union of the two sperm ducts.The latter have definite coats of cu'cular muscles but are not muchthickened. Their union produces a small seminal vesicle, also witha coat of circular fibers, and this continues into an ejaculatory ductthat enters the base of the penis papilla.The female gonopore, distinct from but not far behind the malepore, leads into a vertical female antrum, from which the widenedvagina proceeds dorsally, then makes a sharp bend posteriorly,descending to enter the small Lang's vesicle. The common oviductwas seen below the duct leading to Lang's vesicle but its exact pointof entrance into this duct was not determinable in the sections.Specimen: USNM 28640, anterior part as whole mount, postoralpart as sagittal sections (one slide).Remarks: The original description of Latocestus pacificus is someager that certain identification with this species is probably im-possible. The present identification must be regarded as merelyplausible. It is based on the small size at sexual maturity and theeye arrangement. Laidlaw (1903a) gave the size of the type specimenwith some doubt as 12 mm. and stated that gonopores were presentalthough the gonads were immature. Although the gonads could notbe seen in the present whole specimen because of its opacity, thecopulatory apparatuses indicate full sexual maturity at a length of11 mm., but the specimen is somewhat contracted and was longer inlife. The eye arrangement, especially the long and somewhat pairedmedian streak and the short backward extent of the marginal bands,is very like that shown in the one and only figure of L. pacificus. Theanterior end of the latter, however, appears abnormally shortenedand part may be missing. Laidlaw unfortunately did not depict thelocation of the brain with reference to the median streak of eyes andit is impossible to beUeve his statement that the brain was located at4 mm. from the anterior end of a worm 12 mm. long.Family Plehniidae Bock, 1913Plehnia tropica, new &peciesFigure Id-/Material: Several specimens, of which five were usable, takenfrom the alcyonacean Nephthea by the Stanford team at the PalauIslands, Sta. 254, reef south of Ngaremediu, east end of Urukthapel,Oct. 27, 1955.
POLYCLAD FLATWORMS?HYIVIAN 547General characters: This is a very small species, of broadly ovalform, about 2 mm. long and about half as wide (fig. Id), broadest atthe middle and decreasing slightly to the rounded ends. It is whitewith sprawling black marks in a longitudinal row along each side butsome of these are associated with developing clusters of eggs. Eyesare totally wanting. In the center is seen a small ruffled pharynx andbehind this, directed backwards, the large prostatic vesicle, posteriorlyencased in a conical pointed penis stylet. Behind the tip of the stylet,the cement glands of the female apparatus are noticeable. Groupsof eggs in various stages of development are evident in the interior anda cluster of a few very large, presumably ripe eggs was conspicuousin most specimens at a level between the pharynx and the prostaticvesicle, on each side. These were presumably enclosed in the uteri.They seem very large for the size of the worm. Branches of theintestine, not shown in the figure, could be seen in the whole mountradiating to the periphery and passing back to either side of theprostatic vesicle.Histology: One specimen was mounted whole and the other fourwere sectioned, two in the sagittal plane and two transversely.Because of lack of proper fixation the histological condition was un-satisfactory and yielded little definite information. Epidermis waslacking everywhere but subepidermal musculature could be detectedhere and there. The whole interior appeared as a fibrous mesh con-taining nuclei. Even branches of the intestine were scarcely recogniz-able. Ovaries and testes are relatively large and about fill the thick-ness of the body, hence cannot be said to be either dorsally or ventrallylocated. The large eggs noted in the whole animal were found to bevery yolky, filled with large eosinophilous spheres and covered with alayer of dark bodies. The brain could not be definitely identifiedeither on the whole mount or in the series of sections.CopuLATORY apparatus: This was satisfactorily worked out on oneseries of sagittal sections and is shown in sagittal view in figure le.The large oval prostatic vesicle, of the free type, is the most conspicu-ous part of the male apparatus. It has a fairly thick muscular walland a glandular interior of eosinophilous nature. It is oriented some-what vertically with a forward slant; distally it continues with asharp bend as the penis papilla which has a horizontal orientation.The elongate penis papilla is housed in a male antrum of the sameshape. At its distal end the penis papilla is encased in a sclerotizedcone taking the eosin stain that may be regarded as a penis stylet.A cross section through this part of the penis papilla is shown infigure If. The stylet is covered with a thin layer containing flattenednuclei and is lined by a cuboidal epithelium continuous with the liningepithelium of the unsclerotized part of the penis papiUa. Anterior to
548 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io8the proximal end of the prostatic vesicle is found the small, muscularseminal vesicle from which the ejaculatory duct proceeds, passingabove the prostatic vesicle and continuing along the posterior side ofthe latter and dorsal to the penis papilla to open just behind the malegonopore or perhaps, one should say, in common with it. This iscertainly a very strange course for an ejaculatory duct; one expects itto enter the base of the penis papilla and this is the case in other speciesof Plehnia. However, the course described appeared clearly indicatedin the sagittal series mentioned; it could not be clearly made out inthe other series but neither could any entrance into the penis papillabe found. The ejaculatory duct is composed chiefly of a thin muscularwall of longitudinal fibers.The female apparatus is very similar to that of Plehnia arctica(Plehn, 1896). The female gonopore is found shortly behind theexit of the ejaculatory duct. It leads into a long vagina muchslanted forward and paralleling the ejaculatory duct. About atthe level of the proximal end of the prostatic vesicle the vaginamakes a backward curve and after receiving the common oviductproceeds posteriorly parallel to the vagina as a long duct that ter-minates in a small oval Lang's vesicle. The whole tract consists of acuboidal epithelium in which cell walls were missing and has but aslight muscular investment. The large cloud of eosinophilous cementglands, conspicuous in the whole mount, were in evidence in thesections along the vagina but have been omitted from the figure.Differential diagnosis : Plehnia tropica differs from other eyelessspecies of the genus in the course of the ejaculatory duct and thesclerotization of the distal end of the penis papilla.Holotype: USNM 28641, one whole mount; also USNM 28685,best set of sagittal sections (one slide).Remarks: This is the third eyeless species of Plehnia to be dis-covered. The type of the genus, Plehnia arctica (Plehn, 1896),the first example of an eyeless polyclad, came from Spitzbergen.The second, Plehnia caeca Hyman (1953a) came from the Californiacoast at some depth and was also found to occur in a variant withtwo cerebral groups of small eyes. Whether the association of thepresent species with an alcyonacean is obligatory or accidental cannotbe stated but the large yolky eggs and the relatively large copulatoryapparatus indicate some tendency to parasitism. The total wantof eyes in an acotylean polyclad poses a systematic dilemma as thepresent classification of the Acotylea is based upon eye arrangement.However, Bock (1913) satisfactorily placed Plehnia among theCraspedommata and established the family Plehniidae.
POLYCLAD FLATWORMS?HYMAN 649Section SchematommataFamily Leptoplanidae Stimpson, 1857Stylochoplana minuta, new speciesFigure 2o-cMaterial: One specimen collected from algal washings in the in-tertidal zone, Sept. 22, 1953, on Ifaluk Atoll between Elangalapand Falarik Islets, Sta. 65-D-3. Another specimen, collected by D.Reish, Sept. 4, 1956, on fronds of algae on the reef flat on EniwetokAtoll, Sta. E-79, was doubtfully assigned to this species.General features: This is a very small species; the Ifalukspecimen was 5 mm. long, the Eniwetok specimen 4 mm. long. Butboth specimens were seen to be sexually mature by the presence ofrelatively large eggs in a lateral strand on each side (fig. 2a). Theform is typically leptoplanid, slender, elongated, rounded anteriorly,tapering to a pointed posterior end. Tentacles are wanting. Bothspecimens appeared colorless or white. The eyes of both specimensare not arranged in tentacular and cerebral clusters, as common inthe Leptoplanidae, but form a single irregular row, of 15 eyes on oneside, 12 on the other, in the Ifaluk specimen (fig. 26). They werenot counted in the other specimen. Even in the cleared specimenslittle could be seen of the interior structure except the presence ofeggs.CoPULATORY apparatus: The posterior end of the Ifaluk specimenwas removed and sectioned sagittally. The copulatory apparatusesfound therein are depicted in figure 2c. The gonopores are somewhatdistant from each other (about 0.5 mm.). The male gonopore leadsinto a tubular, slanting male antrum that appeared to widen internallyaround a probable penis papilla but these parts were imperfectlypresent in the sections, hence their representation in figure 2c issomewhat conjectural. The lining epithelium of the male antrumis highly glandular, filled with coarse eosinophilous granules. Thepresence of a penis papilla could not be definitely ascertained. Thereis present an elongated oval prostatic vesicle with muscular walland glandular interior. Beneath its proximal end occurs an ovalmuscular seminal vesicle; the connection of this with the prostaticvesicle was vague in the sections but probably occurs as indicatedby the dotted lines in figure 2c. The expanded spermiducal vesiclefilled with sperm was seen entering the seminal vesicle.The female apparatus was in a better state of preservation thanthe male apparatus and its details could be ascertained. The femaleantrum ascending in a curve from the gonopore is continuous withthe vagina of which the distal part is remarkable for its thick mus-
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24.
Figure 2.
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a-c, Stylochoplana minuta: a, dorsal view; b, eyes enlarged; e, sagittal view ofcopulatory apparatuses, female above, d, e, Notoplana micronesiana: d, dorsal view;f, eyes enlarged. (Explanation on page 597.)
POLYCLAD FLATWORMS?HYMAN 551
cular coat, forming a bulbous vagina. This is slanted almost hori-zontally forward. The vagina then narrows to an apparently sinuousduct but parts here were not as clear as desirable. This sinuousduct receives numerous cement glands; it gradually ascends andfinally curves posteriorly. After receiving from below the commonoviduct it descends posteriorly to terminate in a small pyriformLang's vesicle.The entire Eniwetok specimen (USNM 28670) was sectioned butthe sections proved unsatisfactory. As far as it could be discernedthe female apparatus resembled that of the Ifaluk specimen, havinga bulbous vagina followed by an apparently sinuous glandular sectionof the vagina, but this again was not clear. The male apparatus couldnot be followed satisfactorily and was deficient in the same area asthe Ifaluk specimen. One point was definite; the two gonoporesare close together and the male antrum ascends immediately in frontof the vagina. This may represent a geographic difference betweenthe two specimens; or the two specimens may represent differentspecies of Stylochoplana. The condition of the sexual apparatus ofthe Eniwetok specimen does not justify describing it as a distinctspecies, hence it is doubtfully assigned to Stylochoplana minuta.Differential diagnosis: Stylochoplana minuta is dintinguishedby the small size at sexual maturity, arrangement of the eyes in asingle row on each side, bulbous vagina, and sinuous course of theglandular vagina.Holotype: USNM 28642. Anterior part of the Ifaluk specimenas whole mount, postpharyngeal region as sagittal serial sections(one slide). Notoplana micronesiana, new speciesFigures 2d,e', 3aMaterial: One specimen washed from algae in the intertidalzone, Sept. 4, 1953, Ifaluk Atoll, near south end of Falarik lalet,Sta. 23-E-l.General features: The worm is 18 mm. long, 3 mm. wide, ofelongated slender shape with rounded anterior end, blunt posteriorend (fig. 2d). Probably white in life, it was pale brown preserved.The eyes (fig. 2e) are arranged in a continuous band on each side andare not definitely delimited into cerebral and tentacular clusters. Inthe cleared specimen scarcely anything could be seen of internalstructures. The pharynx was vaguely indicated as shown in figureId, but sexual structm'es were not detectable. However, the post-pharyngeal region was removed and sectioned sagittally; it was foundto contain fully developed copulatory apparatuses.
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14-ti
Figure 3.
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a, Notoplana micronesiana, copulatory apparatuses, male apparatus above;i, juvenile leptoplanid from Ifaluk Atoll; c, juvenile leptoplanid from Majuro Atoll;<f-g, juvenile leptoplanids from the Palau Islands. (Explanation on page 597.)
POLYCLAD FLATWORMS?HYMAN 553CopuLATORY apparatus: This is shown in sagittal view in figure3a. The two gonopores are very close together. The male apparatuscontains an excessively long penis stylet, represented as solid in thefigure, although actually hollow. From the male gonopore the maleantrum ascends dorsally as a tubular canal, widens slightly to accom-modate a penis sheath, then curves slightly backward, continuing toascend, and then turns anteriorly as a long narrow canal with a thickmuscular investment. Anteriorly it gi-adually widens, then cm-vesventrally to a slightly mdened chamber that houses the small penispapilla from which the very long stylet springs. The stylet occupiesthe whole of the very long male antrum and even protrudes from thegonopore. Extending posteriorly from the penis papilla in a hori-zontal plane is seen the oval prostatic vesicle into which the ejacula-tory duct projects as diagnostic of the genus Notoplana. Proximallythe prostatic vesicle is entered by a small oval seminal vesicle withthe usual muscular wall.The female apparatus is also long and tubular. The short tubularfemale antrum ascends from the female gonopore, then widens to avagina that slants dorsally and posteriorly. It is lined by a cuboidalepithelium and has a good muscular investment. After receiving frombelow the common oviduct, the vagina continues unaltered as a longduct of Lang's vesicle that makes an S turn, then proceeds posteriorlyto enter the oval, thin-walled Lang's vesicle of moderate size.Differential diagnosis: Of the many species of Notoplana feware provided with a long penis stylet. The stylet of the presentspecies seems to exceed that of all others in relative length. The eyearrangement and proximity of the gonopores also differentiate Noto-plana micronesiana from other long-stjdetted species of the genus.Holotype: USNM 28643, anterior part as whole mount, copulatoryregion as sagittal serial sections (one slide).Euplana gigos (Schmarda, 1859)Remarks: This is one of the most common and widely spread ofIndo-West Pacific polyclads and is easily recognized by the charac-teristic color pattern, which has been excellently figured in color byLaidlaw (1902) and Kato (1934). This species was previously dis-cussed (Hyman, 1955b), and hence comment here will be limited todistributional records. Four specimens (USNM 28644) were collectedby D. H. Johnson on Oca Point, Guam, June 26, 1945. The largestof these was 90 mm. long, preserved, with the gonopores 15 mm. apart.Five specimens (USNM 28645-USNM 28647) were collected by CadetHand, July 2, 31, and Aug. 2, 1954, at Kapingamarangi Atoll, at thesouthern border of the Caroline Islands. These are new records forthe species but there is little doubt that this polyclad is spread through-
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out the Indo-West Pacific from the coast of Africa to Japan andPolynesia. Juvenile LeptoplanidaeFigure Sb-gMany of the specimens in the material were juvenile leptoplanids,hence not identifiable. One specimen (USNM 28671), collected byReish from algae on Majm-o Atoll, Sta. E-57, Aug. 30, 1956, mightpossibly be Stylochoplana minuta, as judged by the eye arrangement(fig. 3c) ; this worm is 3 mm. long with 18 eyes on one side, 19 on theother. Most of the specimens collected at Ifaluk Atoll in the CarolineIslands were juvenile leptoplanids, apparently all of one species, that,judged by the eye arrangement, are probably either Notoplana micro-nesiana or Stylochoplana minuta. Apparently at the time of collect-ing, September-October 1953, some common leptoplanid of the atollhad been breeding. These baby leptoplanids were washed from algaein the intertidal zone at Stations 29-B-3, 32-F-5, 39-E-4, 40-F-3,84-E-5, 85-G-2, 142-F-3, and 179-184-N-4. Figure 36 gives thegeneral appearance of these young leptoplanids; this one came fromSta. 39-E-4 and has been returned to the U. S. National Museumas a whole mount (USNM 28677). The others (USNM 28678-USNM 28684) have been returned in the original vials.There were five other juvenile leptoplanids (USNM 28672-28676)in the collection made by the Stanford team in the Palau Islands. Asjudged by the eye pattern, none of these is identical with Notoplanapalaoensis Kato (1943), the only mature leptoplanid reported from thePalau Islands. USNM 28672, collected from Sta. 28, July 21, 1955,is 3 mm. long, pale or white, anteriorly expanded, with a few eyesarranged in tentacualr and cerebral clusters (fig. dd). USNAI 28673,from Sta. 47, July 28, 1955, is 2.3 mm. long, dark gray in color, ofslender shape, with eyes in two longitudinal bands (fig. 3e) . USNM28674, from Sta. 60, Aug. 5, 1955, is 2.8 mm. long, of slender ruffledform, probably white, with eyes in two bands (fig. 3/). USNM 28675,taken Oct. 12, 1955, at Sta. 220, is 3.5 mm. long, pale, of broad,elongated form with eyes in two somewhat broad bands (fig. 3g) ;traces of incipient copulatory organs are present. The eye arrange-ment somewhat resembles that of the specimen from Sta. 47 (fig.Ze), but the difference in color precludes identity. USNM 28676,from Sta. 258, Nov. 2, 1955, appears definitely identical with the onefrom Sta. 60 (fig. 3j0 and has not been figm-ed ; it is 4 mm. long, white,thin and ruffled. Tentacles appeared absent in all cases and theusual central elongated ruffled pharynx is present. All have beenreturned to the U. S. National Aluseum as whole mounts.
POLYCLAD FLATWORMS HYIVIAN 555It is puzzling that the collections contain so many juvenile lep-toplanids and so few adult ones. It further appears that a numberof distinct species of Leptoplanidae must be present around thePalau Islands. Family Planoceridae Lang, 1884Aquaplana pacifica, new speciesFigures 4a-c; 5aMaterial: One specimen collected by the Stanford team at Sta,220, Palau Islands, southeastern end of Koror Island in Oj^ster Pass,near east entrance of Iwayama Bay, Oct. 12, 1955.General characters: The specimen is of broadly oval form (fig.4a), measuring 14 by 11 mm., and of a transparent texture but pep-pered vaih. minute brown dots that are very abundant over the copu-latory region but diminished over the pharyngeal area. There aretwo tentacles, contracted to rounded form, that contain no eyes butare also peppered with brown dots. The numerous eyes occur inpaired tentacular clusters and in a loose cerebral group that is notvery definitely paired (fig. 46). From the central ruffled pharynxnarrow intestinal branches radiate to the periphery, and a main in-testinal branch extends anteriorly, subdividing into three. The uteri,stuffed with eggs, begin just behind the tentacles and curve posteriorlylateral to the pharynx, converging to the female copulatory apparatus.The copulatory apparatuses are found somewhat posterior to thepharynx, and because of the transparency of the animal show manydetails prior to sectioning (fig. 4c).Copulatory apparatus : The copulatory region was removed andsectioned sagittally, and the apparatuses are shown in sagittal viewin figure 5a. All parts of the male apparatus are bound within thesame muscular sheath (fig. 4c). The spermiducal vesicles (expandedsperm ducts) approach the male apparatus from behind, and at itssides acquire a thick coat of circular fibers, thus becoming sphericalspermiducal bulbs. Their muscle fibers are continuous with those ofthe rest of the male apparatus (fig. 4c). Prostatic vesicle and cirrussac form one continuous structiu'e with a continuous muscle coat.The anterior end of this structure constitutes the prostatic vesicle,not demarcated from the cirrus sac. It has a thick muscular coat offibers that mostly parallel its external contour and the relativelysmall pyriform cavity is fined by ridges of glandular epithelium,filled with eosinophilous granules. The prostatic duct continues pos-teriorly as the ejaculatory duct, centrally placed in the cirrus sac.This duct shortly receives the short common sperm duct into itsventral side (fig. 5a), formed by the union of the two sperm ducts.
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aFigure ^.?Aquaplana pacifica: a, dorsal view; b, eyes enlarged; c, copulatory apparatusesas seen looking down on whole animal. (Explanation on page 597.)These course separately from the spermiducal bulbs through the thickmuscular wall of the cirrus sac. The cirrus sac is of elongated conicalform, gradually narrowing to the male gonopore. Posteriorly itswall continues as a cirrus papilla, armed with a few teeth, that projectsposteriorly beyond the male gonopore and is basally enclosed in ashort male antrum. There is no other armature of the male apparatusexcept the teeth or thorns on the cirrus papilla.
POLYCLAD FLATWORMS?HYMAN 557The female gonopore, located shortly behind the male gonoporeand almost reached by the protruding cirrus papilla, leads into avertical female antrum from which the long vagina slants anteriorly,paralleling the cirrus sac, then curves backwards and descends towardsthe ventral body wall. The ascending part of the vagina is glandu-lar, lined by a tall epithelium that receives the numerous cementglands. Shortly after curving backward, the vagina alters into astrongly muscular tube with a cuticularized lining. The thick mus-cular wall of interwoven muscle fibers pursuing a mostly circularcourse is well delimited from the surrounding mesenchyme. Afterturning doAvnward, the vagina again alters its histological character,losing the definite muscular coat and becoming lined with a tallcellular epithelium. As it continues to descend, the vagina enlargesinto a sac that receives into its anterior wall the common oviduct; itthen narrows again as the duct of Lang's vesicle that makes an up-ward bend and terminates in a small oval Lang's vesicle (fig. 5a).A copulatory bursa is wanting.Differential diagnosis : Aquaplana pacifica differs from the onlyother species of the genus, A. oceanica (Hyman) (1953b), in the lackof a copulatory bursa and the much smaller size of Lang's vesicle.Holotype: USNM 28648, one whole mount with copulatory regionremoved, the latter as sagittal sections (three slides).Remarks: There is good correspondence between the general andcopulatory anatomy of the two species of Aquaplana. In A. oceanicathe spermiducal bulbs and prostatic vesicle are not quite as closelyincorporated with the cirrus sac as in A. pacifica. In both speciesthe vagina is differentiated into glandular and muscular regions.The want of a copulatory bursa in A. pacifica seems to indicate thatthis structure is not as taxonomically important as previously sup-posed. Its lack in A. pacifica would certainly not warrant separatingthe latter into a distinct genus. The important character of thegenus appears to be the cirrus papilla armed with thorns. In A.oceanica thorns are also present on the wall of the male antrum butthese are wanting in A. pacifica.Paraplanocera fritillata, new speciesFigures 5b-d; 6aMaterial: One specimen taken by Reish from rocks on the reefflat at Eniwetok Atoll, Sta. E-123, Sept. 7, 1956.General characters: The specimen (fig. 56) is of broadly ovalform, measuring 19 by 17 mm., of thin, transparent texture, withruflSed margins. The color is yellowish gray, slightly mottled withbrown, and under magnification a cloud of black dots is seen over
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Figure S.?a, Aquaplana pacifica, sagittal view of copulatory apparatuses, male apparatusto right; b-d, Paraplanocera fritillata: b, entire animal; c, eyes and tentacles enlarged;d, copulatory region as seen from ventral side in cleared animal. (Explanation on page597.)
POLYCLAD FLATWORMS?^HYMAN 559
and around the central organs (pharynx, copulatory apparatuses).Sections show that these dots are located in the mesenchyme and areaggregations of minute black granules. Similar dots are recorded forP. langii (Laidlaw) (1902) and P. rotumanensis Laidlaw (1903a).There is a pair of elongated tentacles situated far back from theanterior margin. At the base of each tentacle is a circle of denselyplaced eyes and between the tentacles are two cerebral groups ofeyes, of 20-25 eyes each (fig. 5c). The rounded ruffled pharynx withcentral mouth is medially located, slightly anterior to the bodycenter. Behind it appears the copulatory apparatus, of which themain parts are easily seen because of the transparency of the body.There are seen (fig. 5d) the round spermiducal bulbs with thickmuscular wall of circular fibers to either side of the prostatic vesicle,the cirrus sac with two large teeth, pyriform copulatory bursa extend-ing anteriorly to one side of the male complex, and the vagina sur-rounded with a halo of cement glands. The copulatory region wasremoved and sectioned sagittally and the remainder of the wormmounted whole.Copulatory apparatus: A sagittal view of the apparatus appearsin figure 6a. The rounded prostatic vesicle forms the anterior end ofthe male apparatus; it has a moderately thick wall of muscle fibersparalleling its external contour and a glandular interior composed ofglandular folds projecting into the lumen and composed of eosi-nophilous granules. The two accessory prostatic vesicles or pocketsfound at the posterior side of the main vesicle and very definitelymarked off in some species, notably P. oligoglena, are here poorly de-fined, although apparently present. A wide prostatic duct leaves theprostatic vesicle and receives at once a relatively long common spermduct into its ventral side. The spermiducal bulbs as they approachthe prostatic vesicle have a firm muscular coat of circular fibers that ismuch thicker on the side towards the vesicle and soon becomes incor-porated into the muscular coat of the latter. Each spermiducal bulbthen narrows to a sperm duct, still with a coat of circular fibers, thatsoon joins its fellow to produce the common sperm duct. The commonsperm duct enters the prostatic duct from below just as the latterleaves the prostatic vesicle. The right spermiducal vesicle does notcoil extensively in front of the bursa as it does in P. oligoglena.The prostatic duct with ciliated epithelial lining, thin but musculardorsal wall, and thicker muscular ventral wall, curves posteriorlyabove the anterior part of the cirrus sac and enters the dorsal wallof this sac at about its middle. The cirrus sac is an oval body withexcessively thick muscular wall. The muscles run mostly at rightangles to the external contours but actually a web of fibers is present.Into the lumen of the anterior part of the cirrus sac there projects a472590?59 2
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very large tooth covered with a cuticularized coat ; at its base a smalltooth is seen on each side but no other teeth were evident in the ante-rior part of the sac. At about the middle there is another similar largetooth with cuticularized surface and distal to this the liunen is linedwith small teeth that increase in size distally to the beginning of themale antrum proper. The antrum is a tubular exit lined by a tallepithelium; its anterior wall forms a pair of glandular pouches thatreceive eosinophilous secretion. Prostatic duct and anterior part ofthe cirrus sac are surrounded by a so-called space that is filled with avague bluish material in stained sections. It seems to be present inaU members of the genus.The female gonopore is well separated from the male pore. Itleads into a short tubular female antrum from which the wider vaginawith much folded walls ascends. Characteristic of the present speciesare two strongly marked cement pockets of the vagina, an anterior anda posterior one. Each receives a great cloud of cement glands. Theposterior pocket is the larger of the two, although this is not evidentin the median section, since it expands laterally, and receives thegreater mass of cement glands. Dorsal to the entrance of these cementpockets, the vagina receives the copulatory bursa from in front, thenproceeds dorsally and curves posteriorly above the posterior cementmass. At this point it receives separately the two oviducts (not shownin the jEigure), then descends as the duct of Lang's vesicle and opensinto the relatively short Lang's vesicle. The female tract of theseparts is lined by a cuboidal to taU epithelium and is rather muscularat first; the muscular investment declines towards Lang's vesiclewhich has scarcely any muscular fibers outside the epithelium.The copulatory bursa, not further illustrated, is an extremely mus-cular pyriform sac that extends anteriorly from the vagina along theright side of the male apparatus to the level of the right spermiducalbulb. The immensely thick muscular wall of a web of muscle fibersgradually diminishes in thickness towards the blind end of the bursaand concomitantly the liunen, which does not seem to be lined by adefinite epithelium, enlarges. At the proximal end of the bursa, thewall is relatively thin, although still muscular, and the lumen quitelarge. The waU is everywhere greatly folded into the lumen. Theinterior, especially proximally, contains a great mass, presumablysperm, but so dense this cannot be determined certainly.Differential diagnosis: This is the ninth species to be assignedto the genus and the question of the validity of these species remainsbaffling. The matter of validity was discussed by Kato (1936),Prudhoe (1945), and H}Tnan (1953a); Prudhoe, especially, was in-clined to reduce the number of species by throwing most into synon-ymy with P. oligoglena. But it now appears to me that insufficient
POLYCLAD FLATWORMS?HYMAN 561
attention has been paid to the available deta,ils about the species. Inview of the unsatisfactory nature of some of the descriptions and thefailure to mention certain points, especially the presence or absence ofaccessory prostatic vesicles and antral glands of the male apparatus,it seems to me we are not in a position to declare definitelj'' that anyone of the species is sjaion^anous with any other.I am reluctant to add another species to this complicated situationbut I am not able to identify my form, with any of the previously de-scribed species. The present specimen resembles P. oligoglena in colorand in the presence of two very large teeth in the cirrus sac butdilTers in the fewer cerebral eyes, the cloud of black dots middorsally,the entrance of the common sperm duct into the prostatic duct, notinto the prostatic vesicle, the poor differentiation of the tv/o accessoryprostatic vesicles, the extreme differentiation of the two cementpouches, and the shorter Lang's vesicle. The conspicuous coils of theright spermiducal vesicle in fi'ont of the biu-sa, typical of P. oligoglena,are wanting.The cloud of black dots in the middorsal region appears to be avery definite character. It can scarcely be overlooked as it is notice-able at once on low magnification. These dots, as already mentioned,are in the mesenchyme. They are not the same as the dots in theintestinal branches mentioned by several authors. It appears thatsuch dots are recorded only for P. langi (Laidlaw) (1902) and P.rotumanensis Laidlaw (1903a). P. langi is described as white, with"two" cerebral ej^es, cylindrical tubular cirrus sac lined throughoutwath spines, short wide prostatic duct receiving the common spermduct, and two "folds" in the cirrus sac. If in fact P. langi regularlyhas only two cerebral eyes this would differentiate it from all otherspecies of the genus. The number of cerebral eyes is of course some-what variable among individuals of the same species but not to thatextent. It is not clear just what is meant hj the folds in the cirrussac, but apparently they are not teeth. The description of P.rotumanensis is even less satisfactory. The cerebral eyes are rathernumerous, divided into two groups on each side, the intestine givesoff dorsal diverticula containing brown spots, the prostatic ductenters the cirrus sac on the ventral side, the lumen of the cirrus sacis lined throughout with spines, two folds like those of P. langi arepresent, the common sperm duct enters the prostatic duct, and Lang'svesible is rather large and long. It appears impossible to reconcileP. fritillata with either of these descriptions. It has a fair number ofcerebral eyes, scarcely divided into two groups on each side, the cirrussac is thick and oval, not tubular, the prostatic duct is rather longand enters the cirrus sac in the middle of its dorsal surface, the lu-men of the cirrus sac rather lacks spines anteriorly, the two very large
562 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 108teeth are definitely not folds, and Lang's vesicle is rather short.The descriptions of P. langi and P. rotumanensis do not mention thepresence of accessory prostatic vesicles or male antral glands butthese structures cannot be presumed to be absent. P. fritillataappears to differ from previously described species of the genus inthe very strongly differentiated cement pockets, one from the anterior,the other from the posterior side of the vagina. There is no pocketassociated with the entrance of the bursa into the vagina as de-scribed for P. misakiensis Yeri and Kaburaki (1918). These cementpockets, the cloud of black dots, the poor differentiation of the ac-cessory prostatic vesicles, the lack of spination of the anterior partof the cirrus sac, and the short Lang's vesicle may be taken to charac-terize P. fritiUata.Holotype: USNM 28649, one whole mount with copulatoryregion removed and sectioned (four slides).Family Callioplanidae Hyman, 1953Asoleniaf new genusDefinition: Callioplanidae without Lang's vesicle; reduced femaletract enters the roof of the male antrum; male copulatory apparatusas in Callioplana. Type species: Asolenia deilogyna.Asolenia deilogyna, new speciesFigure 6b,cMaterial: One specimen collected from algae at the PalauIslands by the Stanford team July 22, 1955, Sta. 30.General characters: This is a very small worm, 2.5 mm. long,colorless, without tentacles, of a moderately elongated shape (fig.66). The eyes are rather few in number, arranged in an arc of abouta dozen eyes on each side (fig. Qb) ; in this arc, four larger eyes oneach side probably represent tentacular eyes. The central ruffledpharynx is encircled anteriorly by the confluent uteri, fiUed with eggs,and ovaries are seen scattered in lateral regions. At first the specimenwas thought to be a juvenile leptoplanid but then the uteri werenoticed, evidencing sexual maturity.Copulatory apparatus: Because of its small size the entire wormwas sectioned sagittally. Examination of the sections revealed sur-prisingly a member of the family Callioplanidae. A sagittal view ofthe copulatory complex is given in figure 6c. The male complex iswell developed and clearly shown on the sections. The oval freeprostatic vesicle with muscular wall of moderate thickness and glan-dular eosinophilous interior is in contact on its ventral side with anelongated, oval seminal vesicle with muscular wall. The duct of the
POLYCLAD FLATWORMS?HYMAN 563
Figure 6.
?
a, Paraplanocera frilillata, sagittal view of copulatory complex, male above.b, c, Asolenia deilogyna: b, entire animal; c, sagittal view of copulatory complex, maleabove. (Explanation on page 597.)
564 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io8prostatic vesicle and the ejaculatory duct of the seminal vesicle meetand unite in the proximal part of the penis papilla and the commonduct so formed extends along the center of the penis papilla to its tip.The penis papilla is an elongated structure with a thick muscularwall covered with an epithelium that is thickened at the penis tipand proximally becomes continuous with the lining epithelium of therather spacious male antrum, which exits ventrally by a narrow tubu-lar passage. Under the epithelium of the male antrum is found aconsiderable muscular investment.The female apparatus is very curious, much reduced, and springingfrom the roof of the male antrum, something quite unusual in poly-clads. This condition could hardly result from contraction on pres-ervation. The female antrum as it leaves the male antrum is a nar-row tube encu'cled by a thick muscular sphincter. The parts of thefemale tract are unfortunately poorly preserved in the sections. Theantrum widens to an ascending vagina that then descends as a tubewith a wall of cuboidal cells. This seems to make a curve and ascendbut preservation was poor here. There next comes an oval glandularpart of the vagina, definitely seen, entered by cement glands. Anarrowed tube leaves this and descends, then widening to a sac thatseems to receive two ducts; the connection with these ducts couldnot be followed although very probably it is as shown in the figure.These two ducts descend behind the male antrum and then curveanteriorly. They seem to be the uteri and could be followed, althoughnot too clearly, to the rear ends of the egg-filled uteri shown infigure 66. It is possible that the two ducts are the double Lang's ves-icle characteristic of the genus Callioplana, but in that case the uteriwould enter the vagina beyond the glandular region and no indicationof ducts here could be found.Holotype: USNM 28686, one set of sagittal sections (one slide).Remarks: Since the female tract was unclear, it was difficult tomake a decision about this worm. If the two ducts discussed aboveare Lang's vesicles rather than uteri, the specimen could be fitted intothe genus Callioplana, with which the male system is in accord al-though the lack of tentacles and the characters of the female systemdisagi'ee with the two known species of that genus: C. marginata(Stimpson) (1857) and evelinae (Marcus) (1954). The matter cannotbe decided until better material is obtained.
POLYCLAD FLATWORMS?HYMAN 565Section EmprosthommataFamily Cestoplanidae . ,Juvenile CestoplanidKemarks: There was present in the material from Ifaluk Atoll onevery juvenile cestoplanid, collected Oct. 1, 1953, from the reefridge at thenorth end of Falarik. A di-a\\ang was not made. It may be recalledthat a juvenile cestoplanid was previously reported from the samegeneral area (Hyman, 1955b), but in view of the immaturity of bothspecimens a specific comparison is impossible. The specimen is de-posited in the U. S. National Museum.Suborder CotyleaFamily Pseudoceridae Lang, 1884Genus Pseudoceros Lang, 1884Remarks: The genus Pseudoceros is one of the largest polycladgenera, comprising at present over 100 valid species. The genus iseasily recognized by the combination of smooth dorsal surface, ten-tacles as upfolds of the anterior margin, and ruffled pharynx. Thespecies, however, are distinguishable mainly on shape and colorpattern and the one is distorted and the other often totally lost inpreserved specimens. Hence the identification of preserved specimensusually offers formidable difficulty. Whether the male apparatus issingle or paired is a useful character and details of the male copulatoryapparatus may be of value in specific diagnoses. It now appears thatthe shape of the pharynx may be decisive. In most species the pharynxhas a compact outline but several species are now known in which thepharynx takes what I have termed the butterfly shape, putting outlateral lobulations that increase in length in the anteroposterior di-rection as in figure 10, c.In 1950 Marcus published a useful list of the described species ofthe genus. In the thought of increasing the usefulness of this list Ihere add some old species overlooked by Marcus and the speciesdescribed since that date: fulminatus (Stimpson) (1855), guttatomar-ginatus (Stimpson) (1855), interrwptus (Stimpson) (1855), albicornis(Stimpson) (1857), coccineus (Stimpson) (1857) , japonicus (Stimpson)(1857), niger (Stimpson) (1857), affinis (Kelaart) (1858), atraviridis(Kelaart) (1858), dulcis (Kelaart) (1858),fuscus (Kelaart) (1858), pur-pureus (Kelaart) (1858), luteus (Plehn) (1897), izuensis Kato (1944),nipponicus Kato (1944), evelinae Marcus (1950), mopsus Marcus(1952), bajae Hyman (1953a), canadensis Hjmian (1953a), mexicanusHyman (1953a), montereyensis Hyman (1953a), coralliferus Hyman(1954), micronesianus Hyman (1953b), and texanus Hyman (1955c).
566 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los
I am of the opinion that Pseudoceros grains Kato (1937, also 1943)is identical with Eurylepta striata Schmarda (1859). To be sure,the former is described as white with black stripes and the latteras buff with dark brown stripes but the identity of size, shape, andcolor pattern outweigh such slight color differences which can becaused by ingested food. As the name striata is preoccupied b}''Eurylepta striata Kelaart (1858), it appears that Kato's name gratusis valid. Therefore the proposal of strigosus by Marcus (1950) tocover the Kelaart-Sclmiarda homonymy is unnecessary.The genus is characteristic of tropical and subtropical waters andappears to center in the Indo-West Pacific area.Pseudoceros perviolaceus, new nameEurylepta violacea Schmarda, 1859, p. 27.Pseudoceros violaceus, Stummer-Traunfels, 1933, p. 3544.Not Planaria violacea Kelaart, 1858, p. 135.Remarks: A specimen referred to this species that was collectedin the Palau Islands, July 22, 1954, was sent to the American Museumof Natural History in a lot of miscellaneous material. No other dataare available. The specimen conforms satisfactorily to the originaldescription and figure and with Stummer-Traunfels' statements madefrom Schmarda's specimen. The original specimen from Ceylonmeasured 60 by 40 mm., the present one 25 by 13, but presumablySchmarda's measm-ements are from life. The present specimen re-tains the shape depicted by Schmarda, that is, is broad across theanterior end and narrows regularly toward the posterior end. Thereis but a single male apparatus as discovered by Stummer-Traunfels.The violet or purple color had dissolved badly in the alcohol whichwas stained a reddish purple, leaving the animal of a uniform mediumbrown color.It was necessary to create a new specific name for Schmarda'sspecies as the name violacea is preoccupied by Planaria violaceaKelaart, which is a Pseudoceros but definitely not identical withSchmarda's species for it has a broadly oval shape and a yellowmargin and middorsal stripe. It appears improbable that Schmarda'sspecies can be a variant of Pseudoceros velutinus as supposed byLang (1884, p. 540), for the shape of this is quite different althoughit, too, has but a single male apparatus.The specimen is retained in the invertebrate section of the AmericanMuseum of Natural History.Pseudoceros bedfordi Laidlaw, 1903Remarks: This large and handsome pseudocerid is easily recog-nized by the distinctive color pattern, accurately depicted by Bock
POLYCLAD FLATWORMS?^HYMAN 567(1913) and Kato (1943). The present specimen (USNM 28650)^was found swimming near the reef at Ifakik Atoll, Aug. 12, 1953.Alive it was stated to be at least 100 mm. long, hence is the largeston record; preserved it measured 35 by 36 mm., having contractedstrongly to a rounded shape whereas the natural shape is an elongatedoval. This species was reported by Kato (1943) from the PalauIslands where it was stated to be common although surprisingly notrecovered in the present material from these islands. It is also re-corded from Singapore, the Philippines, and Heron Island in theGreat Barrier Reef and is evidently widely spread in the westerntropical and subtropical Pacific.Pseudoceros izuensis Kato, 1944Figure 7a-cRemarks: One specimen was taken on a reef in the Palau Islandsby the Stanford team, Aug. 8, 1955, Sta. 69, lagoon margin of reefsoutheast of Malakal Pass. As the original description is brief, anexpanded account of the present specimen appears desirable, espe-cially as there is some slight doubt of its identity with Kato's species.The preserved specimen (USNM 28651) measures 22 by 16 mm.and is of broadly oval shape and thin consistency (fig. 7a). Katogave the length, preserved, as 20 by 13 mm., but 60 by 28 in life.The tentacles as sketched by Bayer in life appear in figure 76; theirappearance in the preserved animal is shown in figure 7c. Theruflied pharynx had ruptured through the ventral surface. Thecolor in life as described by F. M. Bayer, who also took a colorphotograph, was pale green above mottled \vith white and dottedwith black dots, with a median ridge of sepia brown laced with white.The tentacles in life (fig. 76) are sepia brown with white tips and whitespots. The body is encircled by a marginal band of olive greencomposed of radial streaks. Preserved, the animal appears lightgray dotted with black dots with a dark margin and a dark middorsalband laced with white. The radial streaks composing the marginalband are stiU detectable in the preserved specimen. Figure 7aattempts to depict the color pattern. The colois agree well withKato's description except for the tentacles which he described aspurplish and the absence of black at the extreme outer margin.Behind the tentacles is seen the bilobed cluster of cerebral eyes(fig. 7c). This disagrees with Kato's statement that the eyes form asingle cluster although his figure indicates a slight bilobulation.Kato figured the tentacular eyes, not well discernible in the presentspecimen.
> A photograph, in color, of this specimen was published in National Geographic Magazine, vol. 109, No. 4,p. 657, April 1956.
568 PROCEEDINGS OF THE NATIONAL MUSEUM
fei;
Figure 7.
?
Pseudoceros izuensis: a, entire animal; h, tentacles from life; c, tentacles ofpreserved specimen. (Explanation on page 597.)The specimen is sexually mature but because of the rupture of thepharynx, the number of male pores could not be ascertained, althoughtwo are probably present. Kato stated a paired condition of themale apparatus. At the posterior end of the pharynx the femalegonopore with accompanying cement glands is obvious (fig. 7a).The specimen has two suckers, one behind the other, as shown infigure 7a, but this is presumably an anomaly. A central position ofthe sucker is indicated by Kato.
POLYCLAD FLATWORMS?HYMAN 569The small differences mentioned above do not seem adequategrounds for separating the present specimen from Kato's species.Pseudoceros izuensis shows considerable resemblance in color patternto P. viridis (Kelaart) (1858), Ceylon, which according to the descrip-tion and colored figure in Collingwood (1876) also is green with browntentacles, a brown middorsal stripe, and a brown streaky margin;but the dorsal surface is splotched with brown rather than dottedwith black. Contrary to Lang (1884, p. 567), I think viridis(Schmarda) (1859) is not identical with viridis (Kelaart) as the colorpatterns of the two species appear somewhat different. It thereforeis necessary to rename Schmarda's species, and I propose virescens.Pseudoceros habroptiliis, new speciesFigure 8Material: One specimen taken by the Templeton Crocker Expe-dition, No. 1014, June 5, 1933, at Vanikoro Island, in the Solomons.General characters: The worm was badly crumpled and theposterior part could not be straightened. After flattening as much aspossible the worm appeared as in figure 8. It measures 10 by 6 mm.and is probably of elongated oval form. At the anterior end appearthe usual tentacidar upfolds of which one is well preserved whilethe other is contracted and distorted. The tentacular eyes werepoorly discernible; the single oval cerebral cluster is shown in thefigure. The black-and-white color pattern is pretty and distinctive.The worm is white with a narrow, very black border that also edgesthe tentacular folds. Paralleling the margin is a wider band of grayishblack hue and centrally there is a paired band of similar width andcolor. The two median bands converge anteriorly and fuse just behindthe cerebral eyes. The black bands could not be followed posteriorlybecause of damage and crumpling here but the black margin obvi-ously encircles the entire worm. The pharynx had probably been shedas rupture was evident ventrally at the appropriate place. The suckerwas not clearly evident and is shown conjecturally in figure 8. Theworm is juvenile without any traces of the reproductive system.Differential diagnosis: The color pattern is sufficiently distinc-tive.Holotype: USNM 28652, the worm mounted whole.Pseudoceros caeruleocinctus, new speciesFigure 9aMaterial: The single specimen was taken by the Stanford teamat the Palau Islands, Sta. 77, Aug. 10, 1955, crawling on clean sandin a shallow bay on the south shore of Auluptagel Island.
570 PROCEEDINGS OF THE NATIONAL MUSEUM
Figure 8.
?
Pseudoceros habroptilus, entire animal. (Explanation on page 597.)General characters: The preserved worm is of oblong shape,20 mm. long by 12 mm. wide. The tentacular foldings are prominent(fig. 9a), but because of the black color the eyes could not be seenin the cleared worm. The color is described by the collector asvelvety black with a narrow, brilliant blue border. Some trace ofthe blue border remains in the preserved worm. The pharynx wasnot detectable. There is a single male apparatus with the male porelocated 5 mm. from the anterior end. The female pore occurs closebehind the male pore. The sucker is located at about the bodymiddle, 10 mm. from the anterior margin.
POLYCLAD FLATWORMS?HYMAN 571Differential diagnosis: The blue border distinguishes this speciesfrom other black species with a colored border. This pattern, blackwith a narrow border of a bright contrasting color, is common amongspecies of Psevdoceros, but usually the border is red, orange, or yellow,and I know of no previously described species with a blue border.Holotype: USNM 28653, in alcohol.Pseudoceros ferrugineus, new speciesFigure 96,cMaterial: The single specimen was taken by the Stanford teamat Sta. 236a, in Iwayama Bay, Palau Islands, Oct. 20, 1955, crawlingin about a meter of water on the rocky shelf of the east end of KororIsland, in Oyster Pass.General characters: The worm is of elongated oval shape (fig.9b), measuring 18 mm. in length by 11 mm. in width, preserved.The tentacular foldings appear slightly developed, both in the pre-served worm (fig. 9c), and on the color photograph of the live worm.The brilHant coloring in life is preserved on the photograph taken byF. M. Bayer, but, alas, the preserved worm is a dull grayish brown.In life the general color is a bright rusty red blending into a narrowmargin of brilliant orange. The dorsal surface is liberally fleckedwith white on the rusty background and here and there these flecksfuse to form nebulous patches of clear white or tinged with pink inplaces. The white flecks diminish towards the margin where therusty red background is much more in evidence. The bright orangemarginal line is free from spots. There is some indication of a narrowmiddorsal line of pale rust that fades away posteriorly.In the cleared worm (fig. 96) there could be seen the shghtly bilobedcluster of cerebral eyes (fig. 9c), the ruffled pharynx having the but-terfly shape that I have noticed in some species of Pseudoceros, thepair of male pores in the concavity of the last lobulations of thepharynx, the female pore close behind the male pores, and the suckerslightly behind the middle, about 10 mm, from the anterior end.Differential diagnosis: The color pattern is distinctive,Holotype: USNM 28654, in alcohol,Pseudoceros ater, new speciesFiGUBE 9dMaterial: The single specimen was taken by the Stanford teamon Raeldil reef, Palau Islands, Sta, 254, Oct. 27, 1955. It was col-lected at night with a light on the outer reef flat among branchingcorals.General characters: This is a small worm, measuring 9 by 7 mm.preserved, although evidently somewhat contracted, hence longer in
572 PROCEEDINGS OF THE NATIONAL MUSEUM
Figure 9.?a, Pseudoceros caeruleocinctus, entire animal, b, c, P. ferrugineus: h, entireanimal; c, tentacles enlarged, d, P. ater. (Explanation on page 597.)
POLYCLAD FLATWORMS?^HYMAN 573
life. The form is an elongated oval (fig. 9d). The tentacular upfold-ings are well preserved. Beliind them is seen the small, compactruffled pharynx of a few folds, and directly behind this occurs thesingle male gonopore, followed by the female pore. The sucker issituated somewhat posterior to the middle of the worm. Despiteits small size the worm was fully mature and laid a small globularegg mass during the night in the jar in which it had been placed.The color is a uniform very dark grayish black, or practically black,mthout any markings. Because of the black color, eyes could not beseen.Differential diagnosis : There does not seem to be any previouslj^described species of Pseudoceros that is small and uniformly of a dullblack coloration. Pseudoceros velutinus (Blanchard) (1847) is uni-formly black but the black is of a velvety texture and tinged withblue or violet; this species is further quite large, being still not fullymature at a length of 50 mm. Pseudoceros bajae Hyman (1953a)is also quite large, with a pair of male apparatuses.Holotype: USNM 28655, in alcohol.Pseudoceros fulvogriseus, new speciesFigure 10a,bMaterial: One specimen was taken by the Stanford team inGeruherugairu Pass, Iwayama Bay, Palau Islands, Sta. 85, Aug. 12,1955.General characters: The worm is a large, elongated species,50 mm. long, preserved, 20 mm. across the widest part. The exten-sive ruffling of the margins indicates a much greater length whencrawling, extended. The worm appears widest across the middleand tapei-s from this to the rounded anterior end, with tjrpical tentac-ular foldings, and posteriorly to the pointed tail (fig. 10a). The shapeis unusually elongated for the genus. An enlarged view of the tentac-ular foldings is shown in figure 106, which also gives the eye distribu-tion. Shortly behind the tentacles is found the group of cerebraleyes, forming a single large rounded cluster. Behind the cerebral eyecluster is seen the compact ruffled pharynx, surprisingly small for thesize of the worm. Posterior to the pharynx are the two male pores,unusually close together, located 10 mm. from the anterior end.They are followed by the female pore, 13 mm. from the anterior end.The sucker is located at about the middle, 25 mm. from the anteriorend. The worm appeared in breeding condition for the branched,anastomosing uterus (shown on one side only in figure lOo) was veryevident in the cleared specimen.
574 PROCEEDINGS OF THE NATIONAL MUSEUM42
Figure 10.
?
a, b, Pseudoceros fulvogriseus: a, entire animal; h, tentacles enlarged, c, d, P.fuscogriitus: c, entire animal; d, tentacles enlarged. (Explanation on page 597.)The preserved worm is of a uniform medium gray color, marked withdark reticulations, which probably actually are the uterine anasto-moses. A color photograph taken by F. M. Bayer shows that in life
POLYCLAD FLATWORMS?^HYMAN 575the color is light gray flushed with yellowish brown. Along the centerof the median ridge there runs a narrow light line flanked on eachside by yellowish brown. The yellowish brown color deepens nearthe margin which is edged by a very narrow light line. The tentaclesappear brown edged with a light margin. There is some suspicionin my mind that the tawny brown color may be caused, at least inpart, by the presence of ripe eggs in the interior.Differential diagnosis: The worm is characterized by the largesize, elongated shape, small compact pharynx, and color pattern.Holotype: USNM 28656, in alcohol.Paeudoceros fuscogriseus, new speciesFigure 10c,dMaterial: Two specimens were collected by the Stanford team ineel grass in the channel between Peliliu and Ngedebus, Palau Islands,Sta. 37, July 25, 1955.General characters: The worms are of moderate size and generaloval form, tapering posteriorly to a pointed tail (fig. 10c). The largerspecimen measured, preserved, 23 by 10 mm., the smaller one, 16 by8 mm. Both worms were bent in the pharyngeal region and rupturedthere when straightened out, hence it did not appear profitable tosection the copulatory region of one of them as this would probablybe involved in the rupture. The anterior end of the larger specimenwhile cleared is shown in figure 10c?. The tentacles, much distortedby preservation, are provided with numerous eyes and well behindthem is seen the group of cerebral eyes, consisting of two oval clusters.The relatively large ruflled pharynx has the butterfly shape alreadymentioned in connection with P. ferrugineus. The single male poreis embraced by the posterior pharyngeal folds and shortly behind itis seen the female gonopore. The sucker of the larger worm is locatedat about 12 mm. from the anterior end. The usual middorsal ridgeseen in pseudocerids is indistinct here. The main intestine couldbe seen in the posterior part of the worm.Unfortunately, no information is available about the color in lifebut probably it was the same as in the preserved worms. They aredusky grayish brown in color with the anterior central part of asomewhat lighter shade. The extent of the light region is indicatedb}^ the dotted line m figure 10c. The line passes along the edge of thepharynx, slightly behind the sucker, and diverges at the anteriormargin. The boundary between the lighter and darker shades ofgrayish brown is quite sharp.Differential diagnosis: This species lacks very definite charac-teristics but the combination of paired cerebral eye clusters, large472590?59 3
576 PROCEEDINGS OF THE NATIONAL MUSEUM vol. i08
ruffled pharynx of the butterfly type, single male gonopore, andcoloration should aft'ord recognition.Holotype: The larger specimen, USNM 28657.Pseudoceros tristriatuSf new speciesFigure 11aPseudoceros concinnus, Stummer-Traunfels, 1933, p. 3565, fig. 9 on color pi.Not Proceros concinnus CoUingwood, 1876, p. 90, fig. 4, pi, 17.Material : A single specimen was taken from beneath rocks on theseaward shore of Ella Islet, Ifaluk Atoll, western Carolines, Sept. 20,1953, by F. M. Bayer under the auspices of the Pacific Science BoardAtoll Research Program.General characters: The preserved worm (fig. 11a) is of ovalform, measuring 12 by 5.5 nam., but a color photograph taken byF. M. Bayer shows that it is more elongated in life, about 4 times aslong as broad. The preserved worm is entirely black but in life it islight blue with three longitudinal orange stripes. These stripes appearfaintly bordered with black and extend from shortly behind thetentacles almost to the posterior end. The two lateral stripes areconfluent posteriorly behind the median stripe. In the preservedworm the tentacular folds are fairly well retained and a few eyes canbe seen upon them. Behind their bases is a rounded cluster of cerebraleyes but the eye arrangement could not be satisfactorily ascertainedbecause of the dense black color of the preserved worm. The pharynxis of the butterfly type, that is, with pronounced lateral lobes increasingin length posteriorly where they slant backwards. Behind thepharynx the main intestine is conspicuous in the cleared worm, givingoff numerous side branches that enter a dense black network ofintestinal branches spread throughout the body. The sucker islocated about 5 mm. from the anterior end in the preserved specimen.The worm is juvenile, being devoid of any traces of the reproductivesystem.Holotype: USNM 28659, one whole mount.Remarks: Despite the immaturity of the specimen, the very dis-tinctive color pattern justifies giving it a name. I believe thisspecimen is identical with the one figured in Stummer-Traunfels(1933, fig, 9 on col. pi. following p. 3596), which he identified asPseudoceros concinnus (CoUingwood). I believe this identification iserroneous, for Collingwood's colored figure gives an entirely differentcolor pattern: cream with a blue border and blue middorsal stripe.I previously called attention to Stummer-Traunfels' error when Idescribed as P. concinnus specimens from New Guinea (Hyman, 1954).Stummer-Traunfels' colored figure that I regard as identical with the
POLYCLAD FLATWORMS?HYMAN 577
12 _^Jl
Figure 11.
?
a, Pseudoceros tristriatus. b, c, Nymphozoon bayeri: b, female copulatoryapparatus, sagittal view; c, sagittal view of male copulatory apparatus. (Explanationon page 597.)present species differs from it only in that the lateral orange stripesdo not reach as far posteriorly, hence are not confluent behind themedian stripe. This appears an insignificant difference. Stummer-Traunfels' specimen was part of the Semper material collected in thePhilippines and the Palau Islands and not^yet published ; the coloredfigure was made from life by Mrs. Semper.
578 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 108Nymphozoon, new genusDefinition: Pseudoceridae with multiple female apparatuses,arranged in a midventral longitudinal row; sucker wanting; otherwiseas in Pseudoceros.Type species: Nymphozoon bayeri, new species.Nymphozoon bayeri, new speciesFigures 116,c; 12a,bMaterial: Two specimens were taken by the Stanford team, oneon a reef flat at Iwayama Bay, Palau Islands, Sta. 133, Aug. 28, 1955;the other on shallow coral sand and eel grass in the same region,Sta. 85a, Oct. 29, 1955.General characters : This is a very large, handsome, black-and-white pseudocerid of delicate consistency. The larger specimen is70 mm. long by 55 mm. wide, preserved, the smaller one 50 mm. by30 mm. From the ruffling of the margins one may surmise that aconsiderably greater length may be attained in life. A photograph ofthe smaller specimen in life shows it to have been about 75 mm. long.The shape is broadly oval tapering to a somewhat pointed posteriorend (fig. 12a); anteriorly there are present the usual tentacular folds.Figure 12a attempts to depict the striking color pattern. There is anarrow, very black, sharply delimited band along the margin thatalso edges the tentacular folds. Medially there is a moderately broadblack longitudinal band that tapers to a point behind the tentacularfolds and narrows posteriorly, but it could not be followed completelyhere because of dam^age. Between the median band and the marginthere is present on each side a broad lateral band of grayish black huethat also could not be followed to the posterior end. The remainderof the animal is pure white. The large ruffled pharynx with centralmouth is drawn in figure 126. The smaller specimen is definitelydevoid of any indication of the reproductive system but the largerspecimen is fully matm'e. As shown in figure 126, there is a pair ofmale pores behind the pharynx and this is succeeded by a midventrallongitudinal row of eight pores, som.ewhat unevenlj' spaced. Thenature of these pores could not be ascertained without sections andthese showed that they are female gonopores. A sucker is definitelywanting. Bayer took a clear kodachrome of the smaller specimen inmotion viewed from the ventral surface; the lack of a sucker is atonce noticeable.CopuLATORY apparatus: It was unfortunately necessary to removethe anterior median part of the larger specimen for sectioning, as thenature of the row of midventral pores could not be determined other-wise. The sections showed the details of the male apparatuses and
POLYCLAD FLATWORMS?^HYMAN 579
Figure 12.?Nymphozoon bayeri: a, entire anima! drawn from a photograph of the livingspecimen by Mrs. Patricia Isham; h, anterior central region cleared specimen, showingpharynx and gonopores. (Explanation on page 597.)
of the row of eight female apparatuses. The sagittal plane of thesections is not very favorable for the study of the male apparatus asthis is oriented at an angle to that plane. However, one of themfell in part nearly in the plane of the sections and forms the basis forfigure lie. The expanded spermiducal vesicle, containing masses ofsperm, enters the proximal end of an elongated seminal vesicle that isbent upon itself. Its proximal half has a thick muscular wall of
580 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io8
circular fibers. Distally the wall thins and the vesicle then makes asharp bend, diminishing abruptly to a narrowed tube with thin mus-cular wall that parallels the thick muscular part. This tube thenbends again and as a narrowed duct runs close to the oval prostaticvesicle, eventually coming in contact with the prostatic duct. Thetwo ducts run in contact for some distance, then fuse to form anejaculatory duct that passes to the surface. Seminal and prostaticvesicles are imbedded in a muscular area indicated by a dotted linein figure lie. The ejaculatory duct could not be traced into thepenis papilla, a nonmuscular conical elevation occupjdng a broadshallow male antrum and apparently devoid of the usual penis styletcharacteristic of the Cotylea.All eight female apparatuses are approximately identical and oneof them is shown in sagittal view in figure lib. The gonopore leadsinto a deep tubular female antrum having the same histological con-struction as the adjacent body wall. It is lined by an epithelium oftall narrow cells underlain by the usual muscle stratum. At itsinternal end the antrum enters the cement pouch of the vagina butthe epithelium here appeared disrupted, whether normally or as afailure of fixation is not determinable. The cement pouch and theglandular tubular vagina leading inward from it receive a tremendousmass of cement glands on all sides. The vagina then expands and itswall, very thin in the glandular region, widens to a cuboidal epithe-lium of loose texture. The vagina then makes a bend, forward insome of the apparatuses, backward in others, and approaches a largecavity filled with eggs that appears to be a median uterus. Seem-ingly this species has a single median uterus in which the eggs collectrather than the usual paired uteri. All eight vaginas are directedtowards this median uterus but none could be followed directly intoit although some contained an egg or two. The uterus is boundedby a definite epithelial wall in which no openings could be found.However, one must suppose that, at the time of spawning, eggs aredischarged from the uterus through all eight vaginas and out of allthe gonopores. The absence of a sucker is presumably associatedwith the multiplication of female apparatuses that extend into thearea where the sucker would normally occur.Holotype: The larger specimen (USNM 28660) in alcohol is madethe holotype, plus the removed anterior median part as sagittal serialsections (31 slides).Remarks: The multiplication of male apparatuses is common inpolyclads but the multiplication of female apparatuses is rare. Apartfrom anomalies the only comparable case of which I know is that ofCestoplana polypora Meyer (1921), in which also there is present amidventral longitudinal row of female apparatuses ranging in number
POLYCLAD FLATWORMS?HYMAN 581from 5 to 30 in dijfferent individuals. As only one sexual specimenof Nymphozoon bayeri is available it cannot be stated whether thenumber of female apparatuses shows individual vai'iation. The lackof a sucker is unusual but not unique in Cotylea. A sucker is absentfrom Amakusaplana ohshimai Kato (1938a), and this author men-tions two other cotyleans reported as devoid of a sucker; but it mustbe admitted that the sucker is very often difficult to see in preservedspecimens.The color pattern of the present species somewhat resembles thatof Pseudoceros gratus Kato (1937), reported as common off the PalauIslands (Kato, 1943) but not recovered in the present material.Kato's species differs from Nymphozoon bayeri in that the margin hasa mere black line rather than a band, in the much narrower lateralblack stripes, and in attaining sexual maturity at a length of 50 mm.Kato makes no statement about the sucker but declares there is a pairof male copulatory apparatuses. The female apparatus is not men-tioned. As already indicated, it appears to me that Pseudocerosgratus is identical with Eurylepta striata Schmarda (1859) ratherthan, as supposed by Kato, with "Stylochoplana" meleagrina Kelaart(1858), in which the stripes are purplish and the tentacles are "occip-ital," meaning, no doubt, nuchal.Genus Acanthosoon Collingwood, 1876Definition: Pseudoceridae with dorsal surface covered with smallpapillae or tubercles; otherwise as in Thysanozoon.Type species: Acanthozoon armatus (Kelaart) (1858).Acanthozoon nigropapillosus, new speciesFigure 13Material: One specimen found swimming off the reef edge atFalarik Islet, Ifaluk Atoll, Sta. 616, collected by Migel, a native ofSonsorol, Oct. 18, 1953, under the auspices of the Pacific ScienceBoard Atoll Research Program.GexVeral characters: The worm is of broadly oval shape (fig. 13),measuring 15 by 14 mm., preserved. It is black with a pale yellowishborder, present in only a few places as the margin is damaged. Thedorsal surface is covered with low rounded black papillae tipped withwhite, hence to the naked eye the dorsal surface appears black dottedwith white. This appearance is depicted in a small area on figure 13.At the middle of the anterior end the tentacular folds are evident buteyes could not be seen because of the black color. Behind the tentaclesan oval area houses the ruffled pharynx of which only a few folds weredetectable. The mouth opening, posterior to the pharynx middle.
582 PROCEEDINGS OF THE NATIONAL MUSEUM42
Figure 13.
?
Acanthozoon nigropapilhsus, entire worm. (Explanation on page 597.)
is evident. Behind the pharynx are plainly seen the two male poreson hillocks, followed by the median female pore. The sucker, largerthan the hillocks around the gonopores, is conspicuous, located slightlyposterior to the middle. The convolutions of the uteri are seen toeither side in the postpharyngeal region.Differential diagnosis: The black color with black white-tipped papillae is distinctive.Holotype: USNM 28661, m alcohol.Remarks: Marcus (1950) recommended revival of Acanthozoonfor pseudocerids with low dorsal elevations. Eveline Marcus (1955)reduced Acanthozoon to a subgenus of Pseudoceros. However, ifPseudoceros be defined as Pseudoceridae with a smooth dorsal surface
POLYCLAD FLATWORMS?^HYMAN 583(Hyman, 1953a), Acanthozoon cannot become a subgenus of Pseudo-ceros but would more logically be made a subgenus of Thysanozoon,which would then include all pseudocerids witli dorsal elevations.In fact, one may anticipate that difficulty must eventually arise indetermining when the elevations are low enough to fit into Acantho-zoon and when tall enough to fit into Thysanozoon. This dilemma hasnot yet arisen. Eveline Marcus (1955) has listed the species to betransferred to Acanthozoon and this information therefore need not begiven here. I favor retaining the genus Acanthozoon for the specieslisted by Marcus.Acanthozoon albopapillosus, new speciesFigure 14a,6Material: One damaged specimen collected July 22, 1954, in thePalau Islands. No other data available.General characters: The specimen is nearly circular but theposterior part is missing, hence the shape of the intact worm wasprobably oval. The sides are also damaged. The tentacular foldsai"e poorly preserved. A pair of eye clusters can be seen in the tentac-ular region and behind them is a single oval cluster of cerebral eyes.The ruffled pharynx is large and voluminous, so much so that damageand rupture are suggested. Behind the pharynx is seen the suckerwhose pointed shape is probably unnatm'al. There are no indicationsof any part of the reproductive system, hence this must be a largeworm when intact and mature. Because of extensive damage thedimensions of the specimen are of little value. In the longitudinalaxis it measures 26 mm., in width 25 mm. anteriorly, 35 mm. poste-riorly. Despite damage the specimen is worth naming because of thedistinctive color pattern. It is black with flesh-colored marginalband and rounded pinkish buff areas all over the dorsal surface. Theseareas are in general smaller towards the periphery. The pattern isindicated on the right side of figure 14a. The entu'e dorsal surface isthickly strewn with small rounded white papillae, hence this surfaceappears dotted with white to the naked eye. These papillae areindicated in the upper left of figure 14a. The ventral surface is paleexcept for a wide black band subtending the paJe margin. Thisblack band is shown on an upturned fold in the lower left of figure14a. It is quite conspicuous when the worm is viewed from theventral side.Papillae: A small bit of the worm was removed and sectionedto see the structure of the papillae. The histology of the papillae ofAcanthozoon was given by Kato (1934) for A. micropapUlosus and byEveline Marcus (1955) for A. hispidus. Both find that the papillaeare elevations of the mesenchyme covered with a cuboidal epithelium472590?59 4
584 PROCEEDINGS OF THE NATIONAL MUSEUM
r
?w?^
Figure 14.
?
Acanthozoon albopapillosus: a, entire worm; h, section through one of thepapillae. (Explanation on page 597.)
containing eosinophilous granules. In the present species the papillais covered with an epithelium much taller than that of the adjacentbody wall (fig. 146). Rhabdites are present only basally and themuscle layer is much reduced in the papilla. Distally the epitheliumcontains large eosinophilous droplets. Hence it appears that thepapillae are secretory, probably productive of adhesive material.DiFFEREjsriTAL DIAGNOSIS: A. albopapUlosus differs from otherspecies of Acanthozoon in the distinctive color pattern of pinkish buffareas on a black ground, pale marginal band subtended ventrally by ablack band, and numerous white papillae over the dorsal surface.Holotype: The specimen, in alcohol, is deposited in the AmericanMuseum of Natural History.
POLYCLAD FLATWORMS?^HYMAN 585Family EuryleptidaeAcerotisa rugosa^ new speciesFigures 15a-c; 16aMaterial :SLx specimens were taken by the Stanford team in thePalau Islands at Stations 28, 69, 92 (two lots), 220a, and 236 dm-ingJuly, August, and October 1955.General characters: The form is oval (fig. 15). Three of thespecimens (from Stations 69, 92, and 236) were extremely small, lessthan a millimeter in length. These are devoid of any signs of repro-ductive organs and have an eye pattern typical of juvenile Acerotisa.The specmien from Sta. 92 is shown in figure 15a. It is 0.9 mm. long,has one large and one small eye in each marginal group, and four eyesin each cerebral gi"oup, of which three form a row immediately infront of the pharynx. An identical eye pattern occurs in the specimen(also 0.9 mm. long) from Sta. 69 except that each marginal groupincludes an additional small eye. The smallest specimen, from Sta.236, measures 0.6 mm. in length and also has four cerebral eyes oneach side, but the group of three is in front of the single eye; thereare four marginal eyes on each side. The three remaining specimensare all of larger size and show increase in eye number and varyingdegrees of sexual maturity. The specimen from Sta. 28 is shown infigure 156. It is 1.4 mm. long and has seven to eight cerebral eyes oneach side and five eyes in each marginal group. The female gonoporeand the male copulatory apparatus are evident in this specimen; thelatter is seen under the posterior half of the pharynx in the figure.Another worm of about the same size, 1.5 mm. long, from Sta. 220a,has eight cerebral eyes on one side, 10 on the other, and a total ofabout 30 marginal eyes, distorted out of their normal positions.Finally, the largest specimen, from Sta. 92, measures 5 by 3.5 mm.It is fully mature and presumably represents the maximum size ofthe species. Its cerebral clusters contain 9 eyes on one side and 11on the other, and there are about 17 eyes in each marginal group(fig. 15c).All specimens have a rugose dorsal surface caused by bundles ofrhabdites which tend to form little pointed projections, as shown inthe small turned back fold on the upper left of figure 15c. There arealso evident in the largest specimen flask-shaped glands along theperiphery, although these are not as regularly and closely arrangedas in Acerotisa multicelis Hyman (1955a).The small specimens appear colorless or pale but the largest one isreddish brown. The position of the sucker is shown in the figures;it was much distended in the specimen depicted in figure 156. The
586 PROCEEDINGS OF THE NATIONAL MUSEUMT
Figure 15.
?
Acerotisa rugosa: a, very small specimen; b, specimen of medium size; c, matureworm. (Explanation on page 597.)branches of the intestine, of which a few are shown in the lower leftof figure 15c, do not anastomose, at least not to any extent.Keproductive system: As there is only one fully mature specimen,I have forborne to section it. However, most of the details of thereproductive system could be ascertained in the cleared, mountedworm. The female gonopore, encircled by radiating cement glands,is located just behind the root of the pharynx (fig. 15c). To each sideof it are seen the coils of the spermiducal vesicles. Extending back-
POLYCLAD FLATWORMS?HYMAN 587
wards from it on each side occur the coils of the two uteri, filled withlarge eggs. The male copulatory apparatus underlies the left sideof the pharynx and the male gonopore lies at the anterior marginof the pharyngeal cavity (fig. 16a). At the posterior end of thiscavity coils of the spermiducal vesicles can be seen approaching theproximal end of the long fusiform seminal vesicle which is nearly aslong as the pharynx in the specunen, underlying the left side of thisorgan. The seminal vesicle is provided with a coat of circular musclefibers and is filled with a dense mass of sperm. At its distal end theseminal vesicle narrows to a duct that underlies the oval prostaticvesicle, in which the radiations of the glandular interior are clearlyvisible. At the distal end of the prostatic vesicle is seen the shortpenis stylet with truncate tip. Other details are not discernible inthe whole specimen. The fact that the male apparatus lies underthe posterior half of the pharynx in the medium sized specimen (fig.156) is rather puzzling and seems to indicate a forward migration ofthis apparatus with sexual maturity.Differential diagnosis: Acerolisa rvgosa is distinguished by therugose dorsal surface, anterior position of the male gonopore, andshort truncate penis stylet. Of other species with a similar anteriorposition of the male gonopore, A. inconspicua (Lang) (1884) has veryfew eyes, A. meridiana (Ritter-Zahony) (1907) has the intestinalbranches anastomosed to a network, and A. californica HjTnan(1953a) has a long pointed penis stylet.Holotype: USNM 28662, whole mount. The other five specimens(USNM 28663-USNM 28667) are also whole mounts.Remarks: Marcus (1947) listed and gave characters of the sevenvalid species of Acerolisa known at that time. In the same article hedescribed three new species of Acerolisa: piscatoria, leuca, and bituna.Since then there have been named: A. arclica Hyman (1953a), cali-fornica Hyman (1953a), and mullicelis Hyman (1955a). Mentionshould also be made of Oligocladus albus Freeman (1933), which prob-ably belongs to Acerolisa, but the one specimen is so imperfectly knownthat decision is impossible at present.Family ProsthiostomidaeProsthiostomuni exiguum, new speciesFigures 166,c; 17aMaterial: Two specimens were taken by D. Reish on EniwetokAtoll, on coral rock on the inner reef flat, Sta. E-8, Aug. 21, 1956.A third specimen, taken in the same locality and type of habitat atSta. E-2, was so distorted and broken that it was discarded as useless.General characters: This is a very small species, with the two
588 PROCEEDINGS OF THE NATIONAL MUSEUM
Figure 16.
?
a, Acerotisa rugosa, copulatory apparatus as seen from above in whole mount.b, c, Prosthiostomum exiguum: b, entire animal; c, eyes enlarged; d, P. griseum, anteriorend enlarged. (Explanation on page 597.)
specimens measuring 4 mm. and 5 mm. in length (fig. 166). Thespecies is of the usual slender shape, broader anteriorly with roundedanterior margin, tapering behind the pharynx to a blunt posterior end.The color appeared to be a dirty white. The eye arrangement is shownin figure 166, and enlarged in 16c. Along the anterior margin is a
POLYCLAD FLATWORMS?HYMAN 589band of small eyos, not definitel}^ divided at the middle, numberingabout 35 in the 4-mm. specimen (fig. 166), about 40 in the 5-mm.specimen (fig. 16c). The cerebral eyes are large and relatively few innumber, ranging from 8 to 12 on each side, in the two specimens. Amarked feature of the eye pattern is the presence of a single isolatedeye on each side at the level of the anterior end of the cerebral groups.Such a pair of eyes set apart from the cerebral gi-oups is known in anumber of species of Prosihiostomum and therefore is not diagnostic.Some authors speak of this pair of eyes as ventral but in my materialthe pair appears on the same level as the other cerebral eyes. Thelarge tubular pharynx, often partly protruded or discarded on fixation,has remained in situ in the smaller specimen but was missing from thelarger one There appeared to be no median intestinal branch abovethe pharynx. Beneath the posterior end of the pharynx is seen theterminal part of the male apparatus, at the attached end of the pharynxis located the female gonopore, and shortly behind the latter occurs thesucker.CopxjLATORY apparatus: Both specimens are sexually mature.The larger specimen was sectioned sagittally, and a sagittal view of thecopulatory structures is shown in figure 17a. The male and femalegonopores and the sucker lie close together but the distance betweenthe two gonopores is slightly greater than the distance between thefemale gonopore and the sucker. The male gonopore leads into along tubular antrum, slanted forward so as to lie almost parallel tothe ventral body wall. At the anterior end of the male antrum isseen the penis, an oval body containing the usual penis stylet, whosetip is protected by the penis sheath projecting into the antrum as aslight elevation. Details of the penis were not very clear in the sec-tions; the usual eosinophilous granulation, indicative of prostaticsecretion, appeared present in the wall around the stylet. The proxi-mal end of the penis receives the ejaculator}^ duct and the ducts ofthe two accessory vesicles. The latter are the usual round muscularbodies with small lumen and thick wall of circular fibers. They occurone behind the other. The more posterior one lies just behind thelevel of the proximal end of the seminal vesicle; tiie other is locatedon the other side of the seminal vesicle at a level just below the poste-rior end of the latter. The seminal vesicle is retort-shaped, curved onitself; its proximal end is rounded with a thick wall of muscle fibereparalleling its contours ;distally, as the vesicle curves posteriorly parallelto itself, the muscular wall thins. The entrance of the sperm ductsinto the seminal vesicle could not be followed. The spermiducalvesicles swollen with sperm are obvious alongside the seminal vesicle.They have been omitted from figure 17a to avoid complicating it.One occurs above the seminal vesicle and the other below, but the usual
590 PROCEEDINGS OF THE NATIONAL MUSEUM
.13
Figure 17.?a, Proslhiostomum exiguum, sagittal view of copulatory complex, male systemabove, h, P. griseum, entire worm. (Explanation on page 597.)
POLYCLAD FLATWORMS?^HYMAN 591sperm ducts from the spermiducal vesicles into the seminal vesiclecould not be found. The ejaculatory duct issues ventrally from thethinned distal end of the seminal vesicle, turns forward, and pursuesa sinuous course to the proximal end of the penis, accompanied aboveby the duct of the more anterior accessory vesicle, below by the ductof the more posterior one. The penis stylet as seen in the wholespecimen before sectioning is shown to the left of the posterior part offigm*e 166. The male antrum is lined by an epithelium of tall, nar-row cells, outside of which occur considerable layers of circular andlongitudinal muscles. These layers continue along the ventralbody wall to the female pore.The female gonopore leads by a short tubular female antrum intoa vaginal chamber lined by an epithelium of tall, narrow cells, withvery little muscular investment. This again leads by a short narrowpassage into a larger chamber, the glandular vagina, or cement pouch.The cement pouch is lined by an epithelium of less narrowed cells,penetrated by the outlets of the cement glands. The latter siuroundthe cement pouch as a mass of eosinophilous granules in which cellsare not detectable. The cement pouch lacks musculature. From itsanterodorsal side the vagina continues as a tube that receives theuteri about on a level with the posterior accessory vesicle of the malesystem.Behind the female apparatus is seen the sucker, forming a ratherlarge deep pouch lined by an epithelium of exceedingly long narrowcells underlain by a muscular investment about equal to that ofthe ventral body wall with which it is continuous.Differential diagnosis: Marcus (1949, 1950, 1952) listed thedescribed species of Prosfhiostomum, with authors and references, andin the 1952 article added one new species, making a total of 53 mem-bers of the genus. Since then there have been described P. latocelisHjiann (1953a) and P. multicelis Hyman (1955a). As the membersof the genus are all very much alike, specific identification poses adifficult problem. The main characters are the eye pattern andnumber and details of the copulatory apparatuses. A few specieshave a distinctive color pattern but most are white or pale. To de-termine the status of the present specimens, all the original descrip-tions were inspected (except those of Stimpson, 1857, probably un-recognizable) but none could be found agreeing with theu characters.In its small size at sexual maturity P. exigwum differs from most ofthe described species. A pair of eyes set off from the cerebral clustersoccurs in P. siphun cuius, P. monosora, P. drygalskii, P. parvicelis,P. sonorum, P. vulgare, P. delicatum, P. notoensis, and P. nozakensis,but other details of eye pattern and number differ from those of P*exiguum except in P. dnjgalskii and P. vulgare. In these two species
592 PROCEEDINGS OF THE NATIONAL MTJSEXJM vol. los
eye number and arrangement are identical with those of P. exiguumand, in fact, for some time it was thought the present specimensmight be P. vulgare Kato (1938b), but the details of the copulatoryapparatus ai"e UTeconcilable between the two. P. exiguum is thendistinguished by the following combination of characters: small sizeat sexual matm-ity, uniform pale coloration, eye pattern (fig. 166, c),long cylindrical male antrum almost horizontally oriented, retort-shaped seminal vesicle, issuance of ejaculatory duct posteriorly andventrally, and female apparatus of two successive chambers.Holotype: USNM 28668, the larger specimen as whole moimt.The smaller specimen (USNM 28687) is deposited as sagittal serialsections (one slide).Prosthiostomum griseuni, new speciesFigures 16d; 176Material: One specimen collected by D. Reish at Parry Island,Eniwetok AtoU, on the lagoon side in September 1956.General characters: This is a very small worm, 4 mm. long, ofthe slender shape characteristic of the genus (fig. 176). It is of auniform dark gray coloration. The eye pattern (fig. IQd) is veryunusual in the genus. The marginal eyes, relativelj^ few in numberand rather large, are not arranged in the usual marginal band but ai'escattered over the anterior end between the cerebral eyes and theanterior margin. The cerebral e3^es occur in the usual two groupsof 8-10 eyes each. The tubular pharynx is partly protruded. Thesucker occurs unusually far posterior to the pharynx, about 0.8 mm.behind the root of the latter. The specimen is juvenile with only thebegimiings of gonads and no indication of copulatory apparatuses.It has such distinctive characters, however, that giving it a specificname appears justified.Differential diagnosis: The scattering of the mai'ginal eyes overthe anterior end is seen in only one other of the 56 described speciesof Prosthiostomum; namely, in P. latocelis Hyman (1953a). Thelatter, however, is pale, mth numerous cerebral eyes, and with thesucker close to the root of the pharynx. The present species isreadily distinguished by the gray color, scattering of the marginaleyes over the anterior end, and posterior position of the sucker.Holotype: USNM 28669, a whole mount.Remarks: Kato (1938a) created the genus Amakusaplana for aprosthostomid identical with Prosthiostomum except that all eyes arescattered over the anterior end and a sucker appears wanting. Thespecies Prosthiostomum latocelis and P. griseum constitute forms inter-mediate between t3^pical Prosthiostomum and Amakusaplana in thattheir marginal eyes are scattered but their cerebral eyes remain in
POLYCLAD FLATWORMS?HYMAN 593definite clusters. The intermediate character of these two speciesgives grounds for doubt that AmakiLsaplana can be maintained as adistinct genus. Collecting StationsFollowing is a list of stations at whicli polyclads were collected inthe Palau Islands by a team composed of R. R. Harry and H. A.Fehlmann of Stanford University and F. M. Bayer of the U. S.National Museum. Geographical coordinates of each locality basedupon Hydgrographic Office charts are noted in parentheses. Num-bers of traverses and islands in Iwayama Bay follow the work ofAbe (1937) and of Abe, Eguchi, and Hiro (1937).Sta. 28. July 21, 1955. Outer reef at eastern end of Urukthapel Island, aboutm miles north of Pkulasuch Point: 7?16'13" N., 134?27'35" E. (H. O. 6103,1st. ed., 1944). Depth 2-4 ft., in breakers; bottom covered with Turbinaria(Acerolisa riigosa, n. sp.; Leptoplanidae, juv.)Sta. 30. July 22, 1955. Iwayama Bay, between south shore of Kaibakku(Island xxix) and Kogai-hant6, Auluptagel Island (traverse xi): 7?19'12" N.,134?29'37" E. (H. O. 6076, 2d ed., 1944). Depth 0-3 ft.; sand, coral, withvegetation consisting mainly of Enhalus and Caulerpa. (Asolenia deilogyna,n. sp.)Sta. 37. July 25, 1955. Middle of channel between Peleliu and NgedebusIslands: 7?2'57" N., 134?16'20" E. (H. O. field chart 4007). Depth 4-8feet; bottom sand with massive coral heads and vegetation of Enhalus ncoro-ides. (Psevdoceros fuscogriseus, n. sp.)Sta. 47. July 28, 1955. Iwayama Bay, in cove formed by west arm of Kogai-hant6, around Islands xxxiii and xxxiv: 7?18'58" N., 134?29'32" E. (H. O.6076, 2d. ed., 1944). Depth, 0-10 ft.; bottoni sand with living and deadcoral with Enhalus growing in sand and Padina on rocky areas. (Lepto-planidae, juv., from sponge washings.)Sta. 60. Aug. 5, 1955. North shore of Koror Island, west of Ebadul's Pier:7?20'48" N., 134?28'12" E. (H. O. 6076, 2d. ed., 1944). Sand flat; occa-sional coral heads, with Enhalus growing on sandy areas, Sargassum attachedto rocks. (Leptoplanidae, juv.)Sta. 64. Aug. 7, 1955. Small bay at southern end of Meherehar (the lagoon ofEil Malk): 7?9'23" N., 134?21'48" E. (H. O. 6078, 1st ed.). Depth 6-20ft.; bottom Hmestone, little sand and scant coral; among sponges, hydroids,and tunicates. (Latoceslus pacificus Laidlaw.)Sta. 69. Aug. 8, 1955. Lagoon margin of reef extending north between eastend of Urukthapel Island and Malakal Pass: 7? 16' 10" N., 134?27'26" E.(H. O. 6103, 1st ed., 1944). Depth 3-4 ft.; Hving and dead coral, rubble;pot holes with sand. (Pseudoceros izuensis Kato; Acerolisa ritgosa, n. sp.)Sta. 77. Aug. 10, 1955. Bay in southernmost coast of Auluptagel Island; inmouth of bay and narrow pass at its middle: 7?17'52" N., 134?29'20" E.(H. O. 6105, 1st ed.). Depth 1-12 ft.; bottomsand, some coral rubble andlimestone; vegetation of eel-grass, Caulerpa, and Halimeda. {Pseudoceroscaeruleocinctus, n. sp.)
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Sta. 85. Aug. 12, 1955. Iwayama Bay, between south shore of Kaibakku(Island xxix) and Kogai-hant6, Auluptagel Island: 7? 19' 12" N., 134?29'37"E. (H. O. 6076, 2d ed., 1944). fApproxinnately the same locality as Sta. 30but a few feet west.) Depth 5-6 ft.; sand and coral, with vegetation ofEnhalus, Caulerpa, and Halimeda. (Pseudoceros fvlvogriseus, n. sp.)Sta. 92. Aug. 14, 1955. Iwayama Bay; south end of Gua-zima (Island xv):7?20'00" N., 134?29'37" E. (H. O. 6076, 2d ed.). Depth 0-20 ft.; sandyflat and fringing reef, with vegetation of Enhalus, Halimeda, Padina. (Acero-tisa rugosa, n. sp.)Sta. 133. Aug. 28, 1955. Iwayama Bay: south shore of Island 11 (traversesviii, ix, x), 7?19'20" N., 134?29'15" E. (H. O. 6076, 2d ed.). Reef flat coveredwith 2-3 feet of water at mean low tide, with pool about 15 ft. deep; bottomcoral and sand, with Enhalus, Halimeda, and Padina. (Nymphozoon bayerin. sp.)Sta. 220. Oct. 12, 1955. Iwaj^ama Bay: east side of Oyster Pass (Kaki-suid6)between Island xxix and east end of Koror. 7?18'57" N., 134?30'09" E.(H. O. 6076, 2d ed.). Bottom limestone, with living and dead coral, depth,3-20 ft. {Aquaplana pacifica, n. sp.; Leptoplanidae, juv.)Sta. 220a. Oct. 22, 1955. Locahty as for Sta. 220. {Acerotisa rugosa, n. sp.)Sta. 236. Oct. 18, 1955. Iwayama Baj^, somewhat north of position of Sta.220: 7?19'00" N., 134?30'11" E. (H. O. 6076, 2d. ed.). Limestone shelfwith living and dead coral, depth 3-20 ft. {Acerotisa rugosa, n. sp.)Sta. 236a. Oct. 20, 1955. Locality as for Sta. 236. {Pseudoceros ferrugineus,n. sp.)Sta. 254. Oct. 27, 1955. Outer reef (called Raeldil) south of Ngaremediu, eastcape of Urukthapel Island: 7?14'37" N., 134?27'11" E. (H. O. 6078, 1sted.). Reef flat with sand patches among living and dead coral, depth 2}^ to3}i ft. (awash at spring tides); collected by the light of gasoline lanterns,just before midnight. {Plehnia tropica, n. sp.; Pseudoceros ater, n. sp.).Sta. 258. Nov. 2, 1955. East side of Urukthapel Island, in small bay north ofNgaremediu Peak, at end of trail leading to Palau Lighthouse (not func-tional): 7?15'57" N., 134?26'55" E. (H. O. 6103 xx ed.). Bottom sand andlimestone, with living and dead coral; Enhalus and Halimeda. {Lepto-planidae, juv.). ReferencesAbe, Noboru1937. Ecological survey of Iwayama Bay, Palao. Palao Trop. Biol. Stat.Stud., vol. 1, No. 2, pp. 217-324, 42 figs.Abe, Noboru; Eguchi, M.; and Hiro, F.1937. Preliminary survey of the coral reef of Iv.ayama Bay, Palao. PalaoTrop. Biol. Stat. Stud., vol. 1, No. 1, pp. 17-35, 1 text fig., 2 pis.,chart.Blanchard, Emile1847. Recherches sur I'organisation des vers. Ann. Sci. Nat., Zool., vol. 8,pp. 271-275, 2 pis.Bock, Sixten1913. Studien uber Polycladen. Zool. Bidr., vol. 2, pp. 31-344, 67 figs.,8 pis.
POLYCLAD FLATWORMS?HYMAN 595Colli NGWOOD, C.1876. On 31 species of marine planarians, collected partly by the lateDr. Kelaart, F. L. S., and partly by Dr. CoUingwood, F. L. S., inthe eastern seas. Trans. Linnaean Soc. London, ser. 2, zool., vol. 1,pp. 83-98, 3 col. pis.Freeman, Daniel1933. The polyclads of the San Juan region of Puget Sound. Trans. Amer.Microsc. Soc, vol. 52, pp. 107-146, 40 figs.Hyman, Libbie Henrietta1953a. The polyclad flatworms of the Pacific coast of North America. Bull.Amer. Mus. Nat. Hist., vol. 100, pp. 265-392, 161 figs.1953b. Some polyclad flatworms from the GaMpagos Islands. Allan HancockPacific Expeditions, vol. 15, pp. 183-210, 6 pis.1954. The polyclad genus Psexidoceros, with special reference to the Indo-Pacific region. Pacific Sci., vol. 8, pp. 219-225, 2 figs.1955a. Some polyclad flatworms from the West Indies and Florida. Proc.U. S. Nat. Mus., vol. 104, pp. 115-150, 9 figs.1955b. Some polyclad flatworms from Polynesia and Micronesia. Proc.U. S. Nat. Mus., vol. 105, pp. 65-82, 5 figs.1955c. A further study of the polyclad flatworms of the West Indian region.Bull. Mar. Sci. Gulf Caribbean, vol. 5, pp. 259-268, 8 figs.Kato, Kojiro1934. Polyclad turbellarians from the neighborhood of the Mitsui Instituteof Marine Biology. Japanese Joum. Zool., vol. 6, pp. 123-138,14 figs., 1 pi.Notes on Paraplanocera. Japanese Journ. Zool., vol. 7, pp. 21-29,5 figs.Polyclads collected in Idu, Japan. Japanese Journ. Zool., vol. 7,pp. 211-232, 24 figs., 2 pis.1938a. Polyclads from Amakusa, southern Japan. Japanese Journ. Zool.,vol. 7, pp. 559-576, 26 figs., 2 pis.1938b. Polyclads from Seto, middle Japan. Japanese Journ. Zool., vol. 7.pp. 577-593, 20 figs., 2 pis.Polyclads from Palao. Bull. Biogeogr. Soc. Japan, vol. 13, pp. 79-90,14 figs., 1 pi.Polycladida of Japan. Journ. Sigenkagaku Kenkyuso, vol. 1, pp.257-318, 62 figs., 4 pis.Kelaart, E. F.1858. Description of new and little known species of Ceylon nudibranchiatemollusks and zoophytes. Journ. Ceylon Branch Roy. Asiatic Soc,for 1856-1858, pp. 134-139, 1 fig.Laidlaw, Frank Fortescue1902. The marine Turbellaria with an account of the anatomy of some of thespecies. In Gardiner, The fauna and geography of the Maldiveand Laccadive Archipelagoes, vol. 1, pt. 3, pp. 282-311, 16 figs.,2 pis.1903a. Notes on some marine Turbellaria from Torres Straits and thePacific, with a description of new species. Mem. Proc. Man-chester Lit. Philos. Soc, vol. 47, No. 5, 12 pp.1903b. On a collection of Turbellaria Polycladida from the Straits of Malacca(Skeat Expedition). Proc. Zool. Soc. London, pp. 301-318, 5 figs.,Ipl.
1936.1937.
1943.1944.
596 PROCEEDINGS OF THE NATIONAL MUSEUM vol. losLang, Arnold1884. Die Polycladen (Seeplanarien) des Golfes von Neapel und der angren-zenden Meeresabschnitte. Fauna und Flora des Golfes vonNeapel. Monogr. xi, 688 pp., 54 figs., 39 pis.Marcus, Ernesto1947. Turbelarios marinhos do Brasil. Zoologia (Sao Paulo, Brazil), No. 12,pp. 99-214, 21 pis.1949. Turbellaria brasileiros (7). Zoologia (Sao Paulo, Brazil), No. 14,pp. 7-155, 22 pis.1950. Turbellaria brasileiros (8). Zoologia (Sao Paulo, Brazil), No. 15,pp. 5-191, 34 pis.1952. Turbellaria brasileiros (10). Zoologia (Sao Paulo, Brazil), No. 17,pp. 5-187, 32 pis.1954. Turbellaria brasileiros. XI. Pap. Avuls. Dep. Zool. Seer. Agr..Sao Paulo, Brazil, vol. 11, pp. 419-489, 71 figs.Marcus, Eveline du Bois-Reymond1955. On Turbellaria and Polygordius from the Brazilian coast. Zoologia(Sao Paulo, Brazil), No. 20, pp. 19-53, 6 pis.Meter, Frieda1921. Polycladen von Kosier (Rotes Meer). Arch. Naturg., vol. 87, Abt.A, Fasc. 10, pp. 138-158, 8 figs., 3 pis.Plehn, Marianne1896. Neue Polycladen gasammelt von Herrn Kapitan Chierchia bei derErdumschiffung der Korvette Vettor Pisani. Jenaische Zeitschr.Naturw., vol. 30, pp. 137-176, 6 pis.1897. Drei neue Polycladen. Jenaische Zeitschr. Naturw., vol. 31, pp.90-99.Prudhoe, Stephen1945. On the species of the polyclad genus Paraplanocera. Ann. Mag.Nat. Hist., ser. 11, vol. 12, pp. 195-202, 2 figs.Ritter-Zahony, Rudolph von1907. Turbellarien: Polycladiden. Ergebnisse Hamburger MagalhaenischenSammelreise, 1892-1893, vol. 3, 19 pp., 9 figs., 1 pi.SCHMARDA, LUDWIG K.1859. Neue wirbellose Thiere beobachtet und gesammelt auf einer Reiseum die Erde, 1853 bis 1857 . . . Band I: Turbellarien, Rotatorieuund Anneliden, Halfte I, pp. 1-37, 8 pis.Stimpson, W.1855. Descriptions of some new marine Invertebrata. Proc. Acad. Nat.Sci. Philadelphia, vol. 7, pp. 380-381.1857. Prodromus descriptionis animalium evertebrarum . . . Pars I.Turbellaria Dendrocoela. Proc. Acad. Nat. Sci, Philadelphia, vol. 9,pp. 19-31.Stummer-Traunfels, Ritter von1933. Erganzende Untersuchungen zum Literaturverzeiohnisse. In Bronn,Die Klassen und Ordnungen des Tier-Reichs . . . vol. 4, pp.3485-3566, 138 figs., 1 col. pi.Yeri, Megumi, and Kaburaki, Tokio1918. Description of some Japanese polyclad Turbellaria. Journ. Coll. Sci.Univ. Tokyo, vol. 39, art. 9, 54" pp., 48 figs., 2 col. pis.
POLYCLAD FLATWORMS?HYMAN 597Explanation of Numbered Parts on Figures
1,