DESCRIPTIONS OF NEW SPECIES OF CHITONS FROMTHE PACIFIC COAST OF AMERICA.By Willia:m Healey Dall,Honorary Curator of MoUusks, United States National Museum.
Ill reviewing the West American Mollusca for the purpose ofcompleting a checklist of Pacific coast Gastropoda, a large numberof Chitons which appeared to be undescribed were found in the col-lection. Part of these were minute, and in the fear that with morethorough study than it was in my power to give at this time theymight prove to be young of species already known, and in view ofthe well-known variability of many groups of these animals it wasthought best to omit them from consideration at present. The othersare now described. I have intentionally referred them to the largergroups on account of the difficulty in determining the value of sub-divisions which have been proposed by recent writers. As thespecimens were all dry it has been impossible in a number of casesto determine the extent of the gill rows, but this has been statedwhenever practicable. The dried specimens, being in various stagesof contraction, it will be understood that the measurements givenmerely approximate those of the living animals.There is little doubt that the west coast of America is the richestChiton region in the world, that many new forms remain to bediscovered and that a satisfactory classification will in time beworked out. The present paper is a small contribution toward thatend. LEPIDOPLEURUS (LEPTOCHITON) AMBUSTUS, new species.Chiton with a rather high but rounded back, the valves reddish-brown with numerous blackish flecks, giving the interspaces a some-what vermicular aspect; anterior valve semicircular, simple; pos-terior valve smaller, shorter, with a subcentral prominent mucro be-hind which the surface is concavely excavated; intermediate valvessubequal, dorsally rounded with hardly any trace of lateral areas;sculpture of the valves nearly uniform fine equal grooves, axially onthe dorsal area, oblique on the lateral areas and cut by still finertransverse striae into microscopic granulations; the distal ends ofthe middle valves in the adult shell with concentric undulations ; in-Proceedings U. S. National Museum, Vol. 55?No. 2283, 499
500 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 53.
sertion plates short, entire; girdle with crowded arenaceous, shortspinules, interspersed near the valve margins with sparse longerwhite spines, the body of the girdle partaking of the colors of theshell, with a silvery reflection in certain aspects; extreme edge ofthe eaves finely striated in accordance with the exterior sculpture;interior whitish, the jugal sinus obscure, the sutural laminae narrow,arcuate, widely separated ; a conspicuous median excavation borderedbehind by two winglike, radially grooved, narrow callosities on theinternal face of the valve under the central area of the posteriorvalve. Length of valves, IT ; width, 8 ; height, 3 mm.flabitat.?Sa.ntii Barbara Channel in 20 to 40 fathoms; F. A.Woodworth. Cat. No. 274120, U.S.N.M.This has som.ewhat the aspect of the European Chiton asellusSpeiigler, which, however, has a differently clothed girdle and isproportionately wider and shorter.It has been known for some years under the above manuscriptname, having been by inadvertence omitted from a paper in whichother chitons were described in 1902.LEPIDOPLEURUS (LEPTOCmTON) LYCURGUS, new species.Chiton minute, white, with touches of brown on either side of thejugal area; dorsum rather angular with flattened sides; anteriorvalve less than semicircular, its edge excavated behind, simple; pos-terior valve axially longer, with a prominent smooth subcentral mucroover a conca^ e posterior slope ; central area axially grooved, minutelygranulose; posterior area with radial granulose very minute sculp-ture; intermediate valves with no marked jugal area, that and thepleural tracts with oblique minute reticulations; lateral areas dis-tinct, radially minutely striate-punctate, with some obscure con-centric undulations distally; girdle spiculose with minute whitespinules of uneven length; interior whitish. Length of valves, 4.5;width, 3 ; height, 1 mm.Habitat.?Catalina Island, California, between tides, collected byW. H. Dall. Cat. No. 274119, U.S.N.M.LEPIDOPLEURUS (LEPTOCHITON) OLDROYDI, new species.Chiton white, with a blackish spot on either side of the jugal area,strongly sculptured; back moderately arcuate, anterior valve semi-circular, sculptured with irregularly disposed small prominent roundpustules; posterior valve with subcentral prominent mucro, the cen-tral area granulose, the periphery pustulose; intermediate valveswith axially puncto-striate jugal area, lateral areas prominent byreason of the conspicuous pustules which are relatively large for thesize of the animal; the pleural tracts coarsely axially grooved, thegrooves more or less distinctly punctate ; girdle with crowded minutespines of equal length, giving an arenaceous effect ; interior whitish,
NO. 2283. NEW PACIFIC COAST CHITONS?BALL. 501the jugal sinus wide with a straight edge, the sutural laminae small,subtriangular. Length of dry animal, 5; Avidth 2; height, 0.7 mm.Ilabifat.?Monterey, California. Cat. No. 218TG7, U.S.N.M.This species was discriminated by Dr. Paul Bartsch some yearsago, but not published.LEPIDOPLEURUS (LEPTOCHITON) AGESILAUS, new species.Chiton small, with a rounded back and verj narrow girdle, thevalves white, but coated with a black deposit (manganese ?) whichobscures the sculpture; anterior valve nearly semicircular, with al-most microscopic radial striation decussated by concentric even finerstriae; posterior valve with a moderately prominent mucro slightlyin front of the center, the central area finely axially puncto-striate,the posterior area radiatelv striate, the ridges more or less granulosofrom intersection by concentric striation; intermediate valves withobscure concentrical undulations which make the posterior edgeirregularly denticulate; pleural tracts and undifferentiated jugalarea axially minutely puncto-striate; girdle minutely densely spinose,the ends of the spinulae forming an arenaceous even surface except atthe outer margin which has a short fringe of slightly longer whitishspinules; interior whitish, the jugal sinus obsolete, the sutural laminaesmall, narrow. Length of animal, 8; width, 5; height, 3 mm. Gillsambient.Hahitat.?Straits of Magellan in Gl fathoms sand, bottom tempera-ture 48? Fahrenheit. United States Fish Commission steamerAlbatross. Cat. No. 96227, U.S.N.M.One of the specimens has only half the seventh valve developed,the vacant space being covered by a widening of the sixth valve onthat side. LEPIDOPLEURUS (LEPTOCmTON) NICOMEDES, new species.Chiton of moderate size, yellowish white, with a moderately widegirdle covered with an even pavement-like series of nearly rectangu-lar subequal ivory-white smooth scales set in radial lines; backalmost keeled, the mucrones of the intermediate valves prominentand whiter than the rest of the surface ; anterior valve semicircularwith faint granular minute radial threads, and a general sculptureof very minute reticulation; posterior valve with a small mucro atthe anterior third, the central area narrow and faintly concentricallysculptured; the posterior area somewhat concave, sculptured likethe anterior valve; intermediate valves without distinct jugal area,that and the pleural tracts sculptured only with a microscopicdecussation; lateral areas conspicuous, with about three radial lowcoarsely granular ribs; interior whitish; jugal sinus inconspicuous,the sutural laminae long, narrow. Length of shell, 10; width, 6.5;height, 4 mm. Gill rows about two-thirds as long as the foot.
502 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55.Habitat.?Off Nelson Strait, southern Chile, in latitude south 51?,52', in 348 fathoms, mud, bottom temperature 49.9? ; United StatesFish Commission steamer Albatross. Cat. No. 96935, U.S.N.M.NUTTALLINA ALLANTOPHORA, new species.Chiton with the broad flattish valves of N. magdalena., feebly mucro-nate, black, with the girdle set with black, white, and brown slightlycurved stout sausage-shaped spines, smaller toward the margin, someover a millimeter long; the interior of the valves a very dark greenwith a very wide shallow sinus; anterior valve semicircular with awhite ray, covered with minute pustules, partly ocular, and a micro-scopic decussation; posterior valve small and axially narrow with aposterior mucro and sculpture like that on the head valve; inter-mediate valves with the jugal area not distinct from the pleuraltracts and the lateral areas indicated only by a faint elevation abovethe pleural tracts and sculptured like the rest of the shell. Length,25 ; width of valves, 15 ; height, 6 mm.TIahitat.?Los Animas Bay, W. J. Fisher. Cat. No. 110360 ?,U.S.N.M.The armature of the girdle is quite sufficient to distinguish thisfrom any of the related species.NUTTALLINA MAGDALENA, new species.Chiton of moderate size with a wide dusky girdle covered withdense microscopic spinules so as to form a velvety surface with a fewlong white spines, more abundant toward the edge of the girdle, whichwith a very narrow strip crosses the region between the valves; thegeneral color is greenish or purplish black, with whitish streaks alongthe dorsal ridge ; the interior is greenish, or white with green in thejugal sinuses; anterior valve with 7 to 9 slits, the outer side of the in-sertion plates striated ; posterior valve with seven slits, the insertionplates smooth ; the intermediate valves with one slit at each end ; an-terior valve semicircular with irregularly scattered globular pustulesand a microscopic fine decussation ; posterior valve wide, short, withterminal mucro, the central area with axial beaded threads with widerinterspaces, the posterior tract pustulate; the intermediate valvesmucronate, with the jugal area simpl}' axially threaded; the pleuraltracts with more or less oblique beaded threads merging laterally intorows of pustules; the lateral areas smooth, not ribbed, with sparselyscattered pustules; internally with the jugal sinus very wide and shal-low, the sutural laminae long and wide. Length, 26; width, 12;height, 7 mm.Hahitat.?Magdalena Bay, Lower California, C. R. Orcutt. Cat.No. 217924, U.S.N.M.This species has very much wider and less interrupted valves thaneither of those previously described, while it is destitute of the strongribbing which they display and has different minor sculpture.
NO. 2283. NEW PACIFIC COAST CHITONS?DALL. 503ISCHNOCHITON MARMORATUS, new species.Chiton small, elegantly marbled with white, gray, and brown, witha velvety girdle covered with mottled gray, white, and brown denselyset spinules; anterior valve with about 12 radial rows of prominentpustules, the rows sometimes bifid, and the ground microscopicallydecussate; slits 8-10; posterior valve smaller, with 8-9 slits, themucro slightly behind the center with a peripheral irregularly doublerow of pustules while the central area is coarsely axially reticulate;intermediate valves with one slit, hardly mucronate, the jugal andpleural tracts axially sculptured with beaded threads finer on thejugum; lateral areas with two or three radial rows of prominentpustules which near the girdle project like little cylinders in an ir-regular manner; interior whitish, with hardly perceptible jugalsinuses and very narrow sutural laminae. Length, 7; width, 4;height, 1.5 mm.Habitat.?Pacific Grove, Monterey Bay, California; Mrs. Blood.Oat. No. 218735, U.S.N.M.Eemarkable for its unusually projecting pustular sculpture. Chi-ton marraoratus Gmelin, belongs to another genus.ISCHNOCHITON BRYANTI, new speciea.Chiton of moderate size, flattish, with dorsal keels, a girdle withoval smooth small imbricating scales mottled with light and darkbrown, the valves light olivaceous brown with blackish flecks ; anter-ior valve less than semicircular, with about 13 rather irregular, some-times bifurcate, thread-like beaded radial riblets, the whole surfacecovered by a microscopic reticulation; internally there are 13-14slits, the insertion plates radiately striated ; posterior margins dentic-ulate, the jugal sinus shallow and small ; posterior valve smaller, thegeneral sculpture on the posterior area like that of the anteriorvalve, internally with 11 slits, the sinus shallow, the sutural laminaenarrow, the insertion plates striated; intermediate valves axiallyshort, slightly mucronate, keeled; the jugal area minutely decus-sate; j)leural tracts with 8-10 prominent axial threads and 6-8 finertransverse threads in the interspaces, the whole valve covered withthe minute decussation; lateral areas with two strong radial minutelynodulous ribs bifurcate distally, the posterior rib annulate, denticu-lating the margin ; internally whitish, with a shallow jugal sinus andone slit in each end. Tjcngth, 9; width, 5.5; height, 2 mm.Habitat.?'' California,"^ F. W. Bryant. Cat. No. 253826, U.S.N.M.This species has the gill rows ambient, and the striated insertionplates are peculiar. It came to the United States National Museumwith the Bryant collection and without any more definite localitythan that above given, but most of his shells were from the southernpart of the State.
504 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55.ISCHNOCHITON BRUNNEUS, new epecies.Chiton of moderate size, flattish, of a yellowish brown with a fewblack flecks on the girdle, which is armed with smooth oval slightly-imbricating scales; anterior valve with 11, posterior with 14, inter-mediate with single slits ; anterior valve with about 16 beaded radialribs sometimes bifurcate, the posterior margin denticulate, the inter-spaces microscopically reticulate; posterior valve flattish, the mucroslightly behind the center, with about 14 sometimes bifid rows of pus-tules with the same reticulate ground ; the central area is sculpturedlike the pleural tracts of the intermediate valves; the latter valveshave a nearly smooth mucro and feeble dorsal carination ; the pleuraltracts have 8 or 10 axial undulated tlireads on each side, beneath whichare more closely set coarser transverse threads with deeply punctateinterstices; the lateral areas have three or four radial ribs, theposterior annulate, denticulating the posterior margin, the othersbeaded, the substratum everywhere with the minute reticulation.Length, 18; width, 12; height, 3 mm.Habitat.?San Diego, California, Henry Hemphill. Cat. No.58734 a, U.S.N.M. ISCHNOCHITON LISTRUM, new species.Chiton of moderate size, straw color, with occasional black blotcheson the girdle, which is densely minutely scaled; though the shell isflattish, the dorsum is nearly keeled, but the valves are hardly mucro-nate; the gill row lacks one-fourth of being ambient; the anteriorvalve has 12, the posterior 11, the intermediate single slits; the anter-ior valve has about 16 thread-like beaded radial riblets, the twomarginal ones are large with half a dozen sharp denticles on theedge ; the whole shell is covered under its stronger sculpture with veryminute reticulation ; the posterior valve is smaller and has 14 ribletslike those on the anterior valve ; the central area is smaller, the mucrobeing low and behind the center; it is sculptured like the pleuraltracts; intermediate valvesAvith a small nearly smooth jugum, the pleu-ral tracts with about a dozen axially straight slender threads on eachtract, with subequal and closer transverse threads in the interspaceswith deep interstices; the lateral areas have two or three slenderbeaded radii on a flat substratum anteriorly, but on the posterior sidethere is a wider rib with five or six widely spaced annulations, whichare projected backward like the teeth of a comb, beyond the margin;internally the valves are whitish. Length, 12; width, 8; height,.2.3 mm.Eahitat.?San Diego, California, Henry Hemphill. Cat. No.58734 &, U.S.N.M.The peculiar sculpture of the lateral areas is the most conspicuouscharacter of this species.
K0.2283. NEW PACIFIC COAST CHITONS?DALL. 505ISCHNOCHITON RITTERI, new species.Chiton of moderate size, brownish, darker on the prominences,witli a rather wide girdle set with smooth oval convex whitish im-bricating scales, the valves nearly mucronate, almost keeled ; anteriorvalve with about 20 flattish radii with narrower interspaces, thewhole covered with a minute oblique decussation ; internally whitish,with 16 slits, the insertion plates smooth, the eaves very narrow;posterior valve with a nearly central low mucro, the posterior tractsculptured like the anterior valve but more faintly, the central areapunctate-reticulate ; internally whitish, with 12 slits, the sinus definedby small notches at each end, straight edged, the sutural lamina? nar-row, elongate; intermediate valves (the first larger than the others)with no defined jugal area, but deeply punctate-reticulate, the puncta-tions coarser toward the margins of the pleural area, lateral areaswith three flattish radii Avith narrower interspaces, all covered withthe minute reticulation; internally white with two slits at each end,one sometimes obsolete; the sinus wide, concave, shallow, betv/eentw"0 faint notches, the sutural laminae narrow ; gill rows ambient.Length, 22; width, 15; height, 5 mm.Habitat.?Channel at Juneau, Alaska, Harriman Alaska Expedi-tion, collected by Professor W. E. Bitter. Cat. No. 218759, U.S.N.M.? ISCHNOCHITON EXANTHEMATUS, new species.Chiton of moderate size, of dark yellowish brown color, lighter onthe jugum, the girdle covered with densely set short spinules whoseends form a minute tessellation on the surface; anterior valve lessthan semicircular, sculptured with concentric incremental lines andover the entire surface with very minute granular pustules ; internallywith about 18 slits, w^ith very short smooth insertion plates and ratherspongy eaves; the posterior valve has similar sculpture on the poste-rior area, the low mucro at the anterior fourth of the valve and thenarrow central area merely transversely striated; internally there are14 slits, the insertion plates faintly striated in part, the suturallaminae very narrow, the sinus hardly perceptible, the color white;intermediate valves hardly mucronate, the jugal area smooth exceptfor microscopic punctations, the pleural tracts with seven or eightaxial thread-like lines w^ith Avider interspaces, minutely punctate,on each side; the lateral areas feebly concentrically ribbed and granu-lose like the end valves; internally with one or two slits indifferentlyon the same valve, the sinus wide, very shallow and ill-defined, thesutural laminae narrow, arcuate. Length, 10; width, T; height,4 mm.Habitat.?Straits of Magellan in 61 fathoms, sand, bottom tem-perature 48?, United States Fish Commission steamer Albatross.Cat. No. 96226, U.S.N.M.
506 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55.ISCHNOCHITON OPHIODERIVIA, new species.Chiton oval, dull flesh color, with greenish flecks, internally bluishgreen, girdle with oval white convex smooth scales of about equal size,the back low, rounded; anterior valve less than semicircular, withimpressed incremental lines, the surface covered with flat rectangularor lozenge-shaped scalelike sculpture resembling snake skin, internallywith nine slits, and smooth insertion plates; posterior valve with themucro moderately prominent, in front of the center, the posteriortract sculptured like the head valve, the central area with extremelyfine, somewhat oblique axial threadlets crossed by incremental lines;internally with nine slits, a rather wide straight-edged sinus and quitenarrow sutural laminae; intermediate valves with no differentiatedjugum, that area and the pleural tracts continuous, sculptured with avery fine oblique reticulation ; lateral areas with the " snake-skin
"
sculpture, without ribs; internally with one slit at each end, a widestraight-edged sinus and arcuate sutural laminae. Length, 15 ; width.12 ; height, 4 mm.Eabifat?Punnmfi, James Zetek (No. 574). Cat. No. 332145.TJ.S.N.M. The " snake-skin " sculpture recalls that on Acanthochi-tona^ but is more compact.ISCHNOCHITON ACELIDOTUS, new species.Chiton whitish, of moderate size, with high but not keeled back,the entire surface except the lateral areas covered with a microscopicoblique reticulation; the girdle provided with densely set small spi-nules, whose distal ends appear at the surface to form a regular pave-ment of small lozenge-shaped scales; the gill rows advance to thesecond valve ; anterior valve smooth, except for the microscopic decus-sation, internally with 14 slits; posterior valve with the same number,the mucro in front of the center, the posterior tract sculptured like theanterior valve, the central area like the intermediate valves; the latterhave a smooth space in the mucronate jugal area, the pleuraltracts have six to eight widely spaced slender axial threads ; the lateralareas incremental lines and extremely minute pustulation. Length,14 ; M idth, 9 ; height, 5 mm.Hahitat.?Magellan Straits in 77^ fathoms, ooze, bottom tempera-ture 46.9?, United States Fish Commission steamer Albatross.Cat. No. 122731, U.S.N.M.ISCHNOCHITON MARIPOSA, new species.Chiton small, profusely marbled with red, white, green, and gray,the pattern different in each specimen, the anterior and second valveconspicuously longer axially and somewhat higher than those suc-ceeding them, the girdle maculated with alternate lighter and darkerpatches; the back rather low, not forming a ridge at the jugum;
NO. 2283. NEW PACIFIC COAST CHITONS?BALL. 507
anterior valve with 9, posterior with 8, intermediate valves with 1slit at each end ; the anterior valve is less than semicircular and is ob-scurely granulose; the surface of all the valves is polished; posteriorvalve is small, with low subcentral mucro, the central area axiallygrooved, the posterior area with low granules interspersed with punc-tations; intermediate valves with the jugal area nearly smooth orwith faint punctations, but not definitely differentiated from thepleural tracts, which are sharply grooved in a generally axial butmore or less vermicular manner; the lateral areas are denticulate ontheir posterior edges and irregularly divaricately strongly ridged;the armature of the girdle is composed of minute densely imbricatedscales; the gill rows are ambient; the jugal sinus shallow, with astraight edge, the sutural laminae subrectangular. wide apart.Leng-th of shell, 8 ; width, 4.5 ; height, 3 mm.Babitaf.?GwU of California, W. J. Fisher. Cat. No. 58865,U.S.N.M.This is another of Dr. Paul Bartsch's manuscript species.ISCHNOCHITON BERRYI, new species.Chiton of moderate size, deep crimson with irregular blotches ofbrown and white on its lateral slopes, and a crimson girdle ofrounded densely imbricated small scales ; gill rows ambient ; anteriorvalve with a nearly smooth mucro, from which radiate about 20more or less corrugated, sometimes bifurcating threads, the wholeoverspread like the rest of the shell by an almost microscopic decus-sation; anterior slits about 12; posterior valve much smaller with asubcentral mucro, from which radiate threads, lilte those on the an-terior valve, in all directions; posterior slits 11; intermediate valveswith one slit, jugal area minutely decussated, almost carinate; lateralareas with usually three corrugated ribs, the nodulation of the pos-terior rib undulating the margin of the valve, but there may be oneor two minor intercalary ribs; the pleural areas are axiall}^ ribbedwith deep decussated interspaces, the ribs growing stronger as theyrecede from the jugal region; interior pink, the jugal sinus hardlymarked, axially striated, merging laterally into narrow sutural lami-na3. Length of shell, 11; width, 7; height, 2.5 mm.Habitat.?Pacific Grove, Monterey Bay, California. Cat. No.193375. U.S.N.M.This is one of Dr. Paul Bartsch's undescribed species.ISCHNOCHITON (STENOPLAX) AETHONUS, new species.Chiton narrow and elongate, of deep rose pink, Avith or withoutwhitish mottling along the dorsal ridge, which is evenly rounded;girdle brownish, covered with a dense coating of short, even, minutespinules of a grayish-white color, giving a smooth arenaceous sur-face; anterior valve more than semicircular, sculptured with equal,
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regularly spaced concentric fine threads with wider interspaces andcovered by a microscopic decussation which is found over the wholesurface of the valves ; anterior slits 11 or 12 ; posterior valve with alow, nearly smooth mucro, slightly in advance of the center anduniform concentric sculpture, as in the anterior valve; there is nodefined central area ; posterior slits 10 or 11 ; intermediate valveswith one slit at each end, the lateral areas slightly convex but notsharply delimited, with the jugal and pleural tracts not separated orlimited, the sculpture the same as on the other valves, but the con-centric threads slightly wavy; interior pink, the jugal sinus veryshallow, wide, indicated by a small notch at each end, straight edged,smooth; the sutural laminae narrow, elongated; length of shell, 11;width, 6.5 ; height, 4 mm.Habitat.?Near Cape San Lucas, Lower California, in 10 fathoms.Cat. No. 218814, U.S.N.M.This is of the same general type as /. Ihnaciformis, but has a sculp-ture totally diiferent from that of that species or /. fallax.ISCHNOCHITON COOPERI ACUTIOR Carpenter, MS.On comparing specimens named by Carpenter in the collection ofthe United States National Museum, the only differences I could per-ceive were that the specimens of the variety acutior were lighter andbrighter in color, more emphatic in sculpture, and apparentlyyounger shells. In a group where color is often without systematicvalue, these differences seem hardly worth}'^ of a name, analogousmutations being most common among Chitons.ISCHNOCHITON (RADSIELLA) AETHALOTUS, new species.Chiton small, flattish, wide, both valves and girdle of an olivaceoustint, the latter densely covered with small oval imbricating scales:anterior valve with about 18 irregularly spaced slits, less than semi-circular, sculptured with fine, close, minutely divaricating incisedlines, among which are sparsely scattered relatively large brownish(ocular ?) pustules; this sculpture is extended over the whole sur-face of all the valves, the pustules showing no regularity, except asomewhat radial arrangement on the posterior valve; there is nosegregated jugal tract and the lateral areas are feebly indicated ; pos-terior valve with 11 slits, the mucro very obscure, subcentral, the in-sertion plates smooth, the sutural laminae small, the jugal sinus shal-low, straight-edged, smooth inside; intermediate valves with 2slits, the first valve axially wider than the second, all with the jugalsinus not defined; the sutural laminae rather wide, the valves notmucronate ; interior color greenish ; gill rows ambient. Length, 12
;
width, 6 ; height, 2 mm.Habitat.?G\\\i of California, W. J. Fisher. Cat. No. 58806c.U.S.N.M.
NO. 2283. NEW PACIFIC COAST CHITONS?DALL. 509The absolutely irregular distribution of the brown pustules if char-acteristic of the species is quite remarkable. They are not polished.ISCHNOCHITON EUCOSMIUS, new species.Chiton small, back high but rounded, surface without eyespots; thesurface variegated with white and sage-green with a tendency towhite spots on the posterior edge of the intermediate valves as inC. dentiens, the interior apple-green; anterior valve with 10 slits,somewhat more than semicircular, obliquely decussated with extremelyline striae, which on the intermediate valves give an effect of divari-cation, this sort of sculpture covers the whole shell ; posterior valvewith 9 slits, and a low blunt mucro in front of which the valve isdepressed; girdle white or maculated with white and gray, covereddensely Avith flattish lozenge-shaped, pavement-like scales; inter-mediate valves with 1 slit at each end, the lateral areas feeblymarked without distinctive sculpture, the sutural laminae narrow, thejugal sinus very shallow, defined by a slight notch at each end.Length, 10; width, 5.5; height, 3.3 mm.Hahitat.?Magdalena Bay, Lower California, C. R. Orcutt. Cat.No. 218194, U.sTn.M.The coloration of the specimens in hand is especially neat, thoughdoubtless in a large number the variations would be extreme.ISCHNOCHITON VENEZIUS. new species.Chiton small, .warm yellow-brown with a whitish " bloom," thegirdle mottled with brown and white, covered with a pavement-likecoating of minute rounded scales; anterior valve with 14; posteriorwith 12; and the intermediate valves with 1 slit at each end;anterior valve nearly semicircular, with over 20 radial rows of smallpustules, for the rest covered with a very minute oblique decussation
;
posterior valve smaller, with mucro low and slightly behind the cen-ter, the posterior tract decussated minutely and with a few scatteredpustules near the margin, the central area reticulate; intermediatevalves mucronate, minutely decussate; pleural tracts with fine lowaxial threading and punctate interspaces; lateral areas with 2 or 3somewhat irregular radial rows of pustules on a minutely decussatedground. Length, 7 ; width, 3.5 ; height, 2 mm.Hahitat.?Near Venice, Los Angeles County, CalifoKnia, Uni-versity of Southern California. Cat. No. 216792, U.S.N.M.This is one of the most elegant of the smaller species of the coast.The jugal sinus is straight edged and the sutural laminae narrow.7 CHAETOPLEURA LACTICA, new species.Cliiton small, cream-colored, often maculated with pale green, withhigh almost carinate back, the girdle spongy with a few small spin-ules and sparse hairs on a leathery basis; anterior valve with 8 or 9
510 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55.
slits, posterior with 2 slits, intermediate valves with single slits;anterior valve with about 10 feeble radii, otherwise minutely punc-tate-reticulate ; posterior valve small, with subcentral mucro andsimilar sculpture; intermediate valves with the jugal and pleuraltracts not separated, mucronate, sculptured with obliquel}' axial veryfine threads with punctate interspaces; the lateral areas bounded bya slender, sometimes beaded rib in front and a marginal thickeningbehind, otherwise sculptured like the rest of the valve; internallywhitish with a wide and shallow jugal sinus and prominent suturallaminae. Length, 8 ; width, 4.5 ; height, 2 mm.IlabitaL?CatQlmii Harbor, California, W. H. Dall. Cat. No.172900, U.S.N.M. CALLISTOCHITON ACINATUS, new species.Chiton small, yellowish white, strongly sculptured; the anteriorvalve with nine nodulous ribs with narrower interspaces, a minutelygranulose surface and about 12 inconspicuous slits; posterior valvewith 18 slits and 6 nodular ribs ; this valve is much smaller, the cen-tral tract is narrow and coarsely reticulate ; intermediate valves some-what mucronate ivith 1 slit at each end ; the sculpture on the lateralareas consists distally of two very prominently pustulate ribs, towardthe dorsal ridge there are only crowded minor pustules; the jugaland pleural tracts are coarsely reticulate, the interspaces deep; thegirdle yellowish with densely crowded microscopic imbricating scales
;
length, 6; breadth, 3; height, 1.5 mm.Habitat.?Shore at San Pedro, California. Cat. No. 218773,U.S.N.M.Though very minute, this does not seem to fit in with the adult ofany of the other species.CALLISTOCHITON CELETUS, new specieg.Chiton of moderate size, pale brownish, with a mottled white andbrownish girdle scaled like the preceding species ; anterior valve with11 nodulous ribs, which, except the closer set posterior pairs, haveabout equal interspaces; this valve has 9 slits, each correspondingto a rib, the posterior valve has 24, but only 6 ribs which are mostlysplit for a short distance distally ; this valve is conspicuously convex,with about. 6 large smooth nodules to each rib, the central tract isnarrow and coarsely axially threaded ; in the intermediate valves with1 slit at each end, the lateral areas comprise two strong ribs withvertically compressed nodules, 8 or 9 to a rib, there is a very nar-row smooth spot on the hardly mucronate jugum, the pleural tractshave near the jugal area 6 or 7 close-set axial threads and be-yond them about the same number of sharp straight axial threadswith wider interspaces crossed by much finer, closer, transversethreadlets ; internally the valves are whitish and the sutural laminae
NO. 2283. NEW PACIFIC COAST CHITONS?DALL. 611appear to join each other in front of the obsolete jugal sinus. Length,10; width, 6, height, 2 mm.11ahitat?Shore at San Pedro, California. Cat. No. 218770,U.S.N.M. CALLISTOCHITON AEPYNOTUS, new species.Chiton 3'^ellowish white, with a keeled back, the girdle as usual inthe group ; anterior valve with 10 annulate ribs and a slit for each rib
;
posterior valve small, low, with only about 5 feeble ribs, and 5slits, the central area reticulate; intermediate valves with a narrowsmooth line at the jugum, and single slits; the pleural tracts sharplyobliquely reticulate with deep interspaces; the lateral areas boundedby 2 strong annulate ribs, the posterior rib wider, the interspacesregularly punctate-reticulate; interior white, the jugal sinus almostobsolete. Length, 15 ; width, 7 ; height, 5 mm.Hahitat.?Puget sound, in 37 fathoms rocky bottom, temperature46?. United States Fish Commission. Cat. No. 225448, U.S.N.M.One of the specimens has the distal nodule of a black color on eachrib, all round the border.CALLISTOCHITON CYANOSUS, new species.Chiton of moderate size, rounded back, and rather low dorsum, thecolor pale blue with interrupted bands of straw-color, the girdlearmature as usual, but rather finer and pale in color; anterior valvewith 11 keeled ribs, a slit to 9 of them; these ribs are crossed by fineconcentric threads with about equal, not punctate, interspaces; pos-terior valve low, with subcentral inucro similarly sculptured, the cen-tral area rather larger than the ribbed portion with 10 or 11 promi-nent axial threads on each side, the interspaces crossed by similarthreads, making a conspicuous reticulation ; in the posterior portionare 8 carinate ribs each with a slit; the intermediate valves withone slit on each end, the lateral areas bounded by 2 strong keeledribs crossed by small equal threads, not punctate in the interspaces,denticulating the posterior edge of the area; jugal areas showing anarrow triangular smooth space, on each side of which are 15 or morestrong straight axial threads, the subequal interspaces reticulated bysmaller threads and the interstices deep ; interior bluish white witha wide straight-edged jugal sinus and rather broad sutural laminae.Length, 13 ; width, 8 ; height, 3 mm.Hahitat.?Long Beach, San Pedro, California, Mrs. Hartwell. Cat.No. 109317, U.S.N.M.This has somewhat the characters of Ischnochiton, toward which itmakes a partial approach.CALLISTOCHITON CHTHONIUS. new species.Chiton of moderate size and dark reddish brown color, includingthe girdle which exhibits small lozenge-shaped imbricating scales
512 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55.uniform over the surface; anterior valve with 11 subcarinate radialribs, the two posterior tending to bifurcate, and nine slits; the ribsare hardly nodulous, and in the type the interspaces are reticulatedonly on the left side of the axis; posterior valve with 13 slits, ninenodulous riblets, the mucro subcentral, the central area axiallythreaded with a median smooth keel; intermediate valves with asmooth narrow keel at the jugum, the pleural tracts with a strongrectangular reticulation; the lateral areas with two strong keeled ribs,the posterior rib bifurcate for most of its length and the distal endssometimes divided; these ribs are more or less nodulous, denticulat-ing the posterior edge of the valve; the interspace between the mainribs is deep and angular ; the insertion plates have a single slit ; theinterior of the posterior valve in dark green, of the other valvesgreenish white; the jugal sinus is very shallow, straight edged andwide, the sutural laminae rather narrow. Length, 21.5; width, 10;height, 5 mm.IlahitaL?San Pedro, California. Cat. No. 109488, U.S.N.M.This is another species which verges toward Ischnochiton.CALLISTOCHITON FISHERI, new species.Chiton light greenish gray, small, strongly sculptured, the girdlecovered with minute closely crowded gray scales giving a velvetyaspect; anterior valve with 12 strong annulate radial ribs withnarrower interspaces, internally with 11 slits; posterior valve withthe mucro behind the center, the central area coarselj?^ irregularlyreticulate, the posterior area elevated, with six strong annulate ribs, aslit to each rib, a roundly excavated jugal sinus and narrow rec-tangular sutm-al laminae; the interior is dark green; intermediatevalves with one feeble slit at each end, excavate rather than mucro-nate at the jugal area which is obliquely reticulate, passing into thepleural tracts which are small, axially threaded, the interstices withminute transverse threads; lateral areas with two annulate ribs,the posterior stronger, denticulating the posterior edge of the valve;internally pale greenish with a wide shallow straight edged jugalsinus and narrow sutural laminae. Length, 10; width, 5; height, 3mm.Hahitat.?Glory of Russia Bay, Tanaga Island, Aleutians, on asponge thrown up by the surf; W. J. Fisher. Cat. No. 110353,U.S.N.M. CALLISTOCHITON DUNCANUS, new species.Chiton small, yellowish white, strongly sculptured, with a velvetygirdle densely covered with minute whitish spinules, fringed a littleat the outer margin; anterior valve with nine strong annulate ribswith subequal interspaces and seven slits; posterior valve with sub-central mucro, the central area axially threaded, the posterior tract
I
NO. 2283. ]fEW PACIFIC COAST CHITONS?DALL. 513
with six slightly elevated ribs, the anterior pair bifurcate, internallywith seven slits, the sinus shallow and rounded, the sutural laminaerather wide and not rounded ; intermediate valves slightly mucronate.the jugal area axially striate and rounded, the pleural tracts axiallythreaded with transverse minuter threads in the interspaces, thelateral areas very narrow with two strong nodulous ribs (sometimesbifurcate) and the posterior margin minutely denticulate: Length,10; width, 4.5; height, 2.2 mm.Hahifaf.?Duncan Island, Galapagos Islands, United States FishCommission steamer Albatross. Cat. No. 218772 U.S.N.M.MOPALIA CHLORIS, new species.Chiton low, wide, of moderate size, of a dark bronze green, withleathery girdle which when fresh had a few slender, sparsely dis-tributed hairs upon it (lost in the dry specimen) ; anterior valve witheight slits, externally with about ten radiating conspicuous threadswith a few feebler shorter intercalary' threads, over the whole ofwhich is a faint very minute oblique decussation; posterior valvesmall, with a very low subcentral mucro and a faint concavewave medially behind, over which is a white ray ; it has two slits anda narrow rounded jugal sinus with wide sutural laminae, the finersculpture is like that of the anterior valve with one or two radialthreads; intermediate valves with one slit, the jugal tract acute, withthe pleural tract sculptured with oval punctures between obliquealmost obsolete minute threads ; the lateral areas defined by a singlecord, otherwise similarly sculptured; interior bluish-white, the jugalsinus narrow, rounded, the sutural laminae broad, the insertion i^latessmooth; gill rows ambient. Length, 19; width, 11; height, 3 mm.Habitat.?San Diego, California ; Mrs. N. Davie. Cat. No. 293686U.S.N.M.This at first sight recalls M. Mndsii or Ugnosa but the sculpture isquite different. MOPALIA GONIURA, new species.Chiton of small size with a high arched back, of a jT^ellowish colorflecked with scarlet; the girdle red, velvety, with numerous sparselyscattered large brown spines (broken off in the type) chiefly near theinner border, and smaller ones scattered near the outer part; gillrows about two-thirds the length of the foot; anterior valve with 8slits, posterior with 4, intermediate valves with single slits ; anteriorvalve with 10 radii, the two marginal wider, otherwise the surfaceis covered with punctate reticulation; posterior valve small, themucro at the posterior third, sculpture of the posterior tract inradial lines of pustules, the central area has very similar orna-mentation ; the posterior sinus is narrow A-shaped, the apex reachingG2055?20?Proc.N.M.Vol.55 34
514 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 55.the mucro, the anterior sinus also narrow and acute, the sutural lam-inae broad; jugal and pleural areas of the intermediate valves notseparated, the sculpture of oblique reticulation with emphaticallypunctate interstices; lateral areas similarly sculptured, bounded oneach side b}^ a slender rib, internally whitish with a narrow notch-like sinus. Length, 12 ; width, 6 ; height, 4 mm.Habitat.?Granite Cove, Port Althorp, Alaska, in 16 fathoms,gravel, collected by W. H. Dall. Cat. No. 208703, U.S.N.M.None other of the northern species has such a deep angular pos-terior sinus. MOPALIA CELETOIDES, new species.Chiton with sculpture almost exactly like No. 218770, except thatthe latter has more globular nodules on the lateral ribs and the pleuraltracts are less coarsely and evenly reticulated. In the present speciesthe anterior valve has 10 radial ribs with wider channeled interspacesminutely reticulated ; the posterior valve, however, entirely different,having a posterior mucro with a small rounded sinus below it, and noribs, the surface being taken up by the central area which has verystraight axial threads minutely annulated, with much finer and closertransverse threads visible in the interspaces; gillrows extending for-ward as far as the fourth valve ; posterior valve with 2 slits, anteriorwith 8, intermediate with one at each end ; intermediate valves withthe lateral areas bounded by two strong ribs, the posterior wider,denticulating the posterior margin; the interspaces minutely re-ticulated; jugum minute with a small smooth mucro, the back slightlykeeled in front of it, the pleural tracts with about 11 strong axialthreads with wider interspaces crossed by regular equal minutethreads. Length, 12 ; width, 5.5 ; height, 2.5 mm.Hahitat.?Forrester Island, Alaska ; G. Willett. Cat. No. 218771,U.S.N.M.This at first glance looks very unlike a Mopalia. Compare Cal-listochiton celetus. Semimopalia, new subgenus.Anterior valves slit, posterior valves with entire insertion plates.MOPALIA (SEMIMOPALIA) GRISEA, new species.Chiton of moderate size with pale olive-gray valves streaked witha darker shade and with a series of pale rays on the dorsal line;girdle leathery with sparse, rather long, often duplex hairs ; anteriorvalve with 7 or 8 slits, posterior valve with no slits, anterior four in-termediate valves with one slit and the fifth and sixth without slits,the insertion plates smooth; anterior valve with 11 or 12 radii, thesurface minutely decussate; posterior valve much smaller with afeeble posterior sinus, the low mucro at the posterior fourth, the
NO. 2283. XEW PACIFIC COAST CHITONS?DALL. 515
surface microscopically decussate without other sculpture ; internallygreenish, with a rather narrow jugal sinus and prominent suturallaminae; intermediate valves polished, slightly mucronate, whollymicroscopicallj^ decussate, without other sculpture except two slendersimple ribs which border the lateral areas; internally greenish andwhite with wide and shallow jugal sinus and narrow arcuate suturallaminae. Length, 20; width, 11; height, 3 mm.Habitat.?Between Cape Pillar and Cape Horn, Tierra del Fuego
;
Stokes. Cat. No. 218734, U.S.N.M.In spite of its gloomy color this is a very elegant species.ACANTHOCHITONA ANGELICA, new species.Since the sculpture of all the species from the west coast is so verysimilar this form perhaps may be best indicated by comparison withthe other known species. The valves are of a bright scarlet andmucronate ; the tufts of bristles are w^hite and only moderatelj^ pro-fuse, the girdle otherwise is covered with short grayish spines ofirregular length and plushlike aspect.From A. avicula Carpenter, it is distinguished by its more centralmucro in the posterior valve, its generally larger valves and narrowergirdle. Nearly the same ditferences separate it from A. diegeiwisPilsbry, and aragonites Carpenter. It has not the profuse silkybristles of Pilsbry 's A. exquislta, nor the broad girdle and peculiarsculpture of Sowerby's A. hirundiniformis. None of these specieshas the intermediate valves so long axially in proportion to theirtransverse width. The form of the valves is almost semicircular, thejugal area axially striated and the remainder of the exposed surfacehas the scaly sculpture usual in this genus. Length, about 11 ; width,5 ; height, 3 mm.Habitat.?Angeles Bay, Gulf of California, W. J. Fisher. Cat.No. 110346, U.S.N.M. TONICIA MIXTA, new species.Chiton of moderate size, mottled or streaked with light brown,scarlet, gray, blackish and white, the back rounded, the valvesmucronate but not keeled, the gill rows ambient, the girdle with adense coating of short spinules with a few scattered longer spines;anterior valve with 8 or 9 slits, posterior with 11 or 12, intermediatevalves with one or two, sometimes differing on opposite ends of thesame valve, the insertion plates striated ; anterior valve small, semi-circular, more or less densely provided with small pustules and ir-regularly distributed polished brown eyespots; there are faint indi-cations of five radial threads which in some individuals might becomestronger; the surface of the whole shell is covered with microscopicpunctation; posterior valve with low central or post central mucro,the central area with coarse axial nodulous threads, the posterior
516 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55.tract pustulose; interior whitish with small narrow straight-edgedjugal sinr.s, and rather wide arcuate siitiiral laminae; intermediatevalves with the first axially wider than the rest, the jugal area wide,axially sculptured with interrupted axial threads or rows ofelongated pustules, the lateral areas ill defined, with only very fewirregularly scattered prominent pustules, more abundant in somespecimens; internally whitish or pale greenish; the jugal sinus nar-row, the margin in all the valves projecting tongue-like; the suturallaminae arcuate. Length, 16; width, 8; height, 4 mm.Habitat.?Angeles Bay, Gulf of California, W. J. Fisher. Cat.No. 110345, U.S.N.M.This belongs to the same group as T. fustulifera., to which it isnearly allied but separated by sufficient characters. The projectionof the margin of the jugal sinus is most prominent in the seventhvalve, but is found in all the intermediate valves. The inner surfaceof this feature is smooth. The coating of the girdle is less leatherythan in the more southern Tonicias, but under the microscope eventhey show minute spinules more or less abundant.TONICIA PUSTULIFERA, new species.Chiton of moderate size, polished, yellowish mottled with darkgreen, dark brown and brown dots, the back rounded, the girdle yel-lovv'ish, densely covered with minute short spinules giving a velvetyaspect and with no fringe of longer spines at the border; anteriorvalve with 8, posterior with 11, intermediate valves with single slits,the insertion plates minutely radiallj'^ striated; anterior valve morethan semicircular with a profusion of minute pustules correspondingto sense organs and leaving a puncture when worn off; otherwisesmooth ; posterior valve smaller with the mucro much in front of thecenter, the central area narrow, sculpture as in the anterior valve,internally with a pink spot, the jugal sinus small and shallow, thesutural laminae long and narrow ; intermediate valves with the firstaxially longer than the others, the valves slightly mucronate, thejugal area narrow and smooth except on the first valve which has afew axial grooves, the pleural tracts smooth except for a few veryfeeble wavy subaxial threads often obsolete on one side of the samevalve, stronger near the jugum and on the posterior valves, and a fewscattered very minute pustules; there are faint traces in spots, of amicroscopic decussation ; lateral areas without ribs, feebly indicated,bearing oblique rows of minute pustules; internally white, pinkishunder the jugum, the jugal sinus narrow, deep, straight edged, thesutural laminae broad, arcuate ; the gill rows ambient. Length about19; width, 10; height, 5 mm.Habitat.?San Pedro, California. Cat. No. 218736, U.S.N.M.