A FOSSIL PORPOISE FROM THE CALVERT FORMATIONOF MARYLAND.
By Remington Kellogg,Of the Bureau of Biological Survey, United States Department of Agriculture.
INTRODUCTION.Our knowledge of the fossil cetacean fauna of the Calvert forma-tion has hitherto been and still is very imperfect, notwithstandingthe description of a number of forms by E. D. Cope. Until latelyimperfect vertebrae represented our entire knowledge of most ofthe cetaceans described from this formation. Notwithstanding therecent explorations of the Calvert Cliffs and the acquisition of anumber of skulls, detailed information as to the zonal range of thecetacean fauna is still wanting. The exact localities for the fossilcetaceans described by Cope and collected by James T. Thomas inCharles County, Maryland, have never been published. In conse-quence the zonal position of most of these specimens will probablyremain unknown, unless subsequent discoveries show that some ofthe fossil cetaceans are limited in their geologic range to one zone.It is very unlikely that any cetacean had such a short geologic range.The collection of fossil cetaceans in the United States NationalMuseum includes a fairly representative assemblage of the cetaceansknown to have frequented the Chesapeake embayment during theinterval in which the Calvert formation was deposited. Most ofthe types of fossil cetaceans necessary to a complete understandingof this material as well as additional specimens from Tertiary marinedeposits of North America have been studied. The object of thepresent paper is to describe a fossil porpoise collected by Norman H.Boss on one of his trips to the Calvert Cliffs on the western shore ofChesapeake Bay, Maryland.For the privilege of describing this fossil cetacean I am indebtedto C. W. Gilmore and J. W. Gidley, of the Division of VertebratePalaeontology, United States National Museum. For permission toexamine types of fossil and living cetaceans I desire to extend mythanks to Dr. Witmer Stone and James A. G. Rehn, of the AcademyNo. 2482
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Proceedings U. S. National Museum, Vol. 63. Art. 14.1
2 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 63.
of Natural Sciences, Philadelphia; to Dr. W. D. Matthew, of theAmerican Museum of Natural History, New York ; and to Gerrit S.Miller, jr., of the Division of Mammals, United States NationalMuseum. Dr. John C. Merriam, president of the Carnegie Institu-tion of Washington, has kept in touch with this work as it progressedand I am indebted to him for assistance.THE GENUS ZARHACHIS COPE.Type.?Zarhachis flagellator Cope, E. D., Proc. Acad. Nat. Sci.,Philadelphia, vol. 20, pp. 186, 189, 1868; vol. 21, pp. 9-10, 1869.Type locality.?Miocene marl of Charles County, Maryland. Cal-vert formation. Upper Miocene.Type specimen.?An anterior caudal vertebra. Cat. No. 11231,Academy of Natural Sciences of Philadelphia.Cope proposed Zarhachis flagellator for two lumbar and twocaudal vertebrae which were assumed to represent three differentindividuals. Three of the vertebrae mentioned in 1868 were sub-sequently withdrawn by Cope and referred to other species. In 1868,Cope referred the genus Zarhachis to the family Delphinidae, butin a later article^ he allocated the genus with the Platanistidae.The original description consists of the following
:
ZARHACHIS Cope.This genus is established on vertebrae wliich bear a general resemblance tothose of P7-isco(lelphinus, but differ in the essential point of having flat andbroad diapophyses of the caudals. It is therefore intermediate betvi^een thatgenus and Delphinapterus. The posterior of the caudals in our museumexhibits a narrowing of the diapophyses, as certain of the lumbars do inPriscodelphintis. ZARHACHIS FLAGELLATOR Cope.This species is represented by only two lumbar and two caudal vertebrae,which belonged to at least three different individuals, none of them adult.Neither is any one entirely perfect, but they indicate a very distinct species,by clear characteristics. All of these vertebrae are of greater length ascompared to the diameter than in any other cetacean known by me exceptthe great Basilosaurus. The lumbars, when compared with those of T. lacer-tosus, differ in their broadly obtuse median line, which offers distinct traceof the two keels. An anterior caudal either exhibits unusually broad dia-pophyses, which are directed downwards, or else is a lumbar with two keels,and a median groove below, which is not seen in any other species. Thecaudals exceed in length those of any other species. One of these, from alarge individual, resembles that of P. atropius in the narrow basis of thediapophysis which is probably narrow, and not perforate. The length of thevertebrae Is nearly double the vertical depth of the articular faces. Thediapophysis is nearly median ; the basis of each neurapophysis is one-halfthe length of the centrum, and median.
1 Cope, E. D., The Cetacea. American Naturalist, vol, 24, p. 615. July 31, 1890.
AUT. 14. MARYLAND FOSSIL PORPOISE KELLOGG.
Length lumbar (epiphyses hypothetical)DepthWidthWidth neural canalLength caudal (one epiphysis supplied)
.
Depth caudalDistance between inferior keelsWidth basis diapophysis
In. Lin.
6.52.03.08.010.54.010.510.5A year later, Cope^ corrected his original description and gave asynopsis of the characters of the species of this genus. It is evidentfrom the following quotation that the genus Zarhachis as amendedby Cope is not a natural assemblage.It was stated to differ from Priscodelphinus in that, while some caudals hadspinous diapophyses, others possessed them flat, but imperforate. A vertebrasupposed to indicate the latter characters I am now compelled to refer to an-other species and probably genus*. Other vertebra assigned to C. flagellatormust be referred elsewhere. A lumbar vertebra represents another species ofprobably the same genus, while a third has evidently pertained to still a thirdspecies. The genus will be characterized by the extraordinary length andslenderness of the lumbar vertebrae, and similar, though slightly abbreviatedform of the caudals. The latter have spinous diapophyses, and in one speciesthe former also. While the width of the articular faces of the centra of thesevertebrae in the typical PriscodeJ'phinus is but a few lines less the length, in thespecies of this genus the diameter of the same is only from four-sevenths toone-half of the length. The nearest approach is made by Priscodelphinus stenus,where this diameter is six-sevenths of the length.
I. Median or anterior caudal with strong longitudinal keel above the diapo-physis?which is therefore probably present on the distal lumbars.Epiphysis thicker, larger Z. flagellatorII. No longitudinal keel on lumbars, Diapophyses broad, flat ; epiphyses thin,large Z. tysonii.III. Diapophyses narrow, subspinous ; epiphyses thin, small. Z. velox.At this time the writer proposes to restrict the application of thegeneric name Zarhachis to flagellator; the allocation of tysonii andvelox will be discussed in connection with other material which isnow being studied. So far as the present evidence goes, there aresome grounds for believing that caudal vertebrae like those ofZarhachis flagellator can properly be associated with the presentspecimen.The caudal vertebra in the Academy of Natural Sciences of Phila-delphia which appears to be the type, and is so labeled, is much wornat both ends, and the anterior epiphysis is missing. The lateralprocesses and the neural spine are broken off ; the neural arch is com-
?Cope, B. D., Proc. Acad. Nat. Sci.. Philadelphia, vol. 21. p. 9. 1869.
4 PROCEEDINGS OF THE NATIONAL, MUSEUM. vol. 6S,plete, the canal narrow and slitlike posteriorly and broadly ovalanteriorly. This vertebra is peculiar in- having the transverse proc-esses set in elliptical depressions, divided posteriorly by a thin ridgeextending back from the base of the process. This depression isbounded superiorly by a longitudinal ridge, above which is anotherdepression at the base of the neural arch. The posterior epiphysisis thick and flat. The articular surface has about 12 or 14 radiatinglines. The double keels ^ are emarginate at the middle, and thesurface of the centrum between them concave. This caudal belongedto a large porpoise as is shown by the following measurements. mm.Length of vertebra (one epiphysis lacking)-. 101Greatest depth of centrum 59Breadth of centrum anteriorly (worn) 55Depth of centrum anteriorly (worn) 53Height neural canal antex'iorly 12Height neural canal posteriorly 27Length of base of neural arch (where margins are vertical) 41Length of base of transverse process (about) 25Height of depres.?>ion surrounding transverse process (measured to eniargi-nation of keel below) . 42A satisfactory comparison of the present specimen and the vertebraupon which Cope based Zarhachis flagellator^ however, is not possibleas the corresponding vertebra was not found. The measurements forthe lumbar vertebrae of the specimen from the Calvert Cliffs andfor the caudal of Zarhachis fiageXlatoT bear out the assumption thatthey belong to the same type of cetacean. In addition to a corre-spondence in size of the vertebrae, there are certain structural pe-culiarities which favor such an association. The posterior lumbarsof the fossil porpoise from the Calvert Cliffs have an elongatecentrum as well as a relative narrow and deep neural canal. Theneural arch does not occupy the full length of the centrum and onthe largest caudal there are double ventral keels and correspondingdevelopment of the depressions on either side. There is no trace,however, of a longitudinal keel above the transverse process. Thetype caudal of Zarhachis flagellator^ as remarked above, is peculiarin having the transverse processes set in elliptical depressions, buton the whole the structural features of this caudal vertebra and thoseof the lumbars described in the following text are of the same generaltype, when one takes into consideration the corresponding differ-ences between the lumbar and caudal vertebrae of the living por-poises, Platanista gangetica and Inia geoffrensis. In addition bothof these specimens were obtained from deposits belonging to the Cal-vert formation.
?Case,. E. C, Miocene Atlas, Maryland Geol. Surv., Baltimore, pi. 14, fig. 3, 1904.
AitT. 14. MARYLAND FOSSIL POEPOISE KELLOGG. 5From the type caudal of Zarhachis fiagellatoi^ and the specimendescribed in the following pages, the following characters have beenderived which are considered diagnostic of the genus.Diagnosis.?General architecture of top of skull as in Lipotesand resembling Platanista in certain details, but with a long attenuaterostrum comprising more than five-sixths of the total length of theskull. The beak is neither bowed upward, nor bent downward, butis approximately straight; the basicranial axis presumably is notstrongly bent downward from the axis of beak. The internal por-tion of the proximal extremity of the premaxilla is thin and plaie-like as in Lipotes and Platanista^ and does not form a convex raisedanterior border to the nasal apertures as in Inia. For more than four-fifths of the total length of the rostrum the raised convex portionsof the premaxillae are closely appressed and parallel each other tothe tip of the rostrum, thus forming the roof for the mesorostralgutter. The presphenoid rises to the level of the premaxilla as inLipotes. The maxillae posterior to the maxillary notches expandlaterally, sheath the internal faces of the thick up-built supraorbitalprocesses of the frontals, and partially roof over the temporal fossae.The zygomatic process of the squamosal is in contact with the post-orbitial projection of the supraorbital process of the frontal. Theexternal pterygoids extend forward beyond the level of the maxil-lary notches and conceal the palatines. The nasal passages are situ-ated anterior to the level of the anterior margins of the squamosals.There is a deep groove between the squamosal and frontal bones intowhich the foramen ovale opens. The total number of teeth exceedsthree hundred. The first tooth on either side of the rostrum is con-siderably larger than any of the following teeth. The enamel crownsof the teeth are ornamented with fine longitudinal striae. The rootsare slightly thickened. The ankylosed symphysial portion of themandibular ramus equals eight-elevenths of the total length of eithermandible.* The periotic bone bears a close resemblance to that of PJatanista.The most important differences consist of a more elongated internalacoustic meatus, and a wider interval between the foramen singulareand the cerebral aperture of the facial canal. The tympanicbone also is very similar in general features to that of Platanista.The hyoid bones differ from those of Platanista and agree in somerespects with those of Inia. They consist of a central portion (basi-hyal) with large, expanded, subcrescentic wings (thyrohyals) and apair of short, anterior, conical projections (ceratohyals). The stylo-hyals are free, elongate, and slightly curved.The atlas is free and possesses both upper and lower transverseprocesses. The greatest length of the atlas is about one-half of thegreatest width across the anterior articular facets, A pair of large
6 PROCEEDINGS OF THE ISrATIONAL MUSEUM. vol. 63,
vertcbrarterial canals pierce the neurapophyses and in additionthere are foramina for the spinal nerves. Ten dorsal and at leastfour lumbar vertebrae are present. As a whole the vertebral columnbears a closer resemblance to Platcmista than to any other livingporpoise. The neural spines are deep, flattened, and rather squarelytruncated on their upper extremities. The transverse processes ofanterior caudals are set in elliptical depressions. The posteriorcaudals are perforated dorso-ventrally by paired arterial canals. Thefirst seven pairs of ribs have capitula articulating with the centra asAvell as tubercula articulating with the transverse processes. Thethree posterior ribs articulate with the transverse process. The firstthree pairs of ribs are compressed and their necks are bent at rightangles to the shafts. The eighth, ninth, and tenth ribs lack necks.The sternum resembles that of Platanista and differs from that ofInia in the absence of vertical conical processes behind the articularfacets for the first ribs.Remains of river porpoises are relatively rare in the Calvert Cliffs,and only one skull and associated skeleton have been obtained. Afew imperfect vertebrae which apparently belong to the same type ofcetacean have been examined by the writer, but these specimens do notwarrant description. Judging by the relative quantity of remainsof fossil cetaceans which have been assembled in institutions towhich acknowledgments have been given, the family Platanistidaeseems to have been outnumbered by long and short beaked dolphinsas well as by whalebone whales during the deposition of the Calvertformation in the Chesapeake embayment.Specimen.?Cat. No. 10485, Division of Vertebrate Palaeontology,United States National Museum. The skeleton of this fossil porpoiseis incomplete. It includes a nearly complete skull. The rostrumis entire and the preservation is excellent, but most of the posteriorend of the cranium, with the exception of the bones which form thevertex, was missing when the skull was collected. The lachrymal^and jugals are missing and the right pterygoids are imperfectlypreserved. The periotic and the two tympanic bones found withthe skull are all imperfect or broken. Both lower jaws are pre-served, though they are badly crushed in the region of the coronoid.The sternum is incomplete. The hyoid bones are perfect and entire.One cervical, ten dorsal, four lumbar and three posterior caudalvertebrae, as well as four chevron bones, were found associated withthe skull. Sixteen ribs and eighteen bones of the paddle also be-long to this specimen.Locality.?The occurrence of the specimen is as follows : Near lati-tude 38? 40' 30" North and longitude 76? 32' West, on the western shoreof Chesapeake Bay, approximately one mile south (1,610 meters) of
ART. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 7Chesapeake Beach, Calvert County, Maryland. Shown on Patuxentquadrangle or Patuxent folio. No. 152, United States GeologicalSurvey.Horizon.?The specimen was discovered and excavated by Nor-man H. Boss on August 8, 1921. It was dug from the cliffs threefeet (0.92 meter) above the water level. The oyster shell zone is notvisible at this point, and lies below the beach level. The specimenwas dug from Shattuck's zone 5 of the Calvert Miocene formationof Maryland.It may seem surprising that the skull of this fossil porpoisemanifests many of the peculiar features of Platanista, Lipotes., andInia. The combination of characters is of much interest, thoughthis form can not be considered an ancestor of any of these livinggenera. Although the skull of this fossil porpoise possesses morefeatures in common with Lipotes than with Inia^ there are obviousdifferences in the details of structural modification which are presentthroughout those parts of the skeleton which are available for com-parison.The resemblance of certain portions of the skulls of Lipotes andPlatanista to this fossil is undoubtedly a common inheritance frommore primitive ancestors. The modifications of the bones which takepart in the formation of the nasal passages and the structuralpeculiarities of the premaxillae are essentially the same in all threeskulls. This fossil skull in common with Platanista possesses alarge expanded external pterygoid, a deep groove between thesquamosal and frontal bones, a zygoma with broad glenoid surface,a supraorbital process in contact with the zj^goma, maxillary teethwith narrow recurved crowns, and a peculiar type of tympanic andperiotic bones.Skulls of Lipotes and Inia may appear more specialized than thatof Zarhachis because of the elevation of the vertex and the shiftingof the nasals to a vertical position. On the other hand, the skullof Zarhachis is characterized by an unusually long attenuated ros-trum, by the great vertical depth of the extremity of the supraorbitalprocess, and by a zygomatic process which extends forward beyondthe level of the anterior wall of the brain case and underlies thepostorbital projection of the frontal. Lipotes possesses a ratherhigh maxillary crest, but the extremity of the supraorbital processis relatively shallow and the rostrum is proportionately shorter thanin Zarhachis; the frontal plate of the maxilla is nearly horizontalabove the temporal fossa and the rostrum is constricted behind thetooth rows. In Inia., however, the outer edge of the frontal plate ofthe maxilla is bent upward and forms a vertical crest above the tem-poral fossa, the extremity of the supraorbital process is less stronglycurved upward, the premaxilla in front of the nasal aperture is
8 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63,
swollen or conspicuously convex internally, and the rostrum is notconstricted behind the tooth rows.As seen from ventral view, the nasal passages of the Platanistaskull are far jDosterior to that which is normal for practically allliving porpoises, for their posterior margins lie in the same levelas the anterior margins of the squamosals. In skulls of Lipotesand Inia, and in practically all of the Delphinidae, the nasal pas- ?sages are situated considerably in advance of the anterior ends ofthe squamosals. The ventral opening for the infraorbital canal inthe skull of Platanista is considerably behind the supraorbitalprocess and entirely within the temporal fossa. In most dolphins,including Lipotes and Inia^ the opening for this canal is situated inadvance of or but slightly posterior to the anterior margin of thesupraorbital process of the frontal and never within the temporalfossa. The optic canal is floored by the frontal bone in Platanistawhile in Lipotes the ventral wall of the canal is missing.The external and internal pterygoids project forward in front ofthe nasal passages in the Platanista skull. In skulls of Lipotes andInia^ the forward projecting external pterygoid is absent and a largeexpanded alisphenoid fills the space between the squamosal, parietal,frontal, and internal pterygoid. Skulls of Lipotes and Inia thuslack one of the characteristic bones of the Platanista skull. It is notsurprising that the external pterygoid should disappear, for it arisesfrom the processus alaris of the basisphenoid and in some cetaceans,including Platanista., prevents the ascending process (alisphenoid)of that bone from appearing in the temporal fossa. The developmentand pressure of air sacs in this region according to Winge may ac-count for the final disappearance of the external pterygoid. The rela-tions of the internal pterygoid, vomer, and maxilla to one anotherare described in another part of this paper (pp. 15-16).The cavity for the brain in the skull of Platanista is relativelysmaller than that of Lipotes. It does not necessarily follow that thebrain of Platanista is either a primitive or a secondarily degeneratedtype. Although more than 40 years have elapsed since the publica-tion of Anderson's notable memoir on Platanista., no additional in-formation regarding the brain of this porpoise has been published.The following quotations* summarize the conclusions reached byAnderson.I may sum up this much of the cerebral anatomy by stating that, so far asthe convolutions and sulci are concerned, this species of dolphin has a brain ofa considerably simpler type than in the porpoise or common dolphin, tendingperhaps to some of the Carnivora, though in such a slight degree as still toImpress it with all the attributes of the complex convoluted cerebrum of the
* Anderson, J., Anatomical and Zoological Researches: Comprising an account of theZoological Results of the Two Expeditions to Western Yunnan in 1868 and 1875. Lon-don (1878), pp. 465, 466-467, 1879.
ART. 14. MARYLAND FOSSIL POEPOISE KELLOGG. 9Cetacea. ? * * All things considered, the brain of Platanista is wantingin the broad rotundity of the whale group generally and so marked in Orcella.To a very limited degree it has Elephantine characters, viz, height andmoderate breath, though one can not regard it in any other light than thatof a modified Cetacean form.The eyes of the Ganges River dolphin are of small size and prob-ably do not function beyond conveying sensory impressions ofvarying degrees of light and darkness. Functional eyes would be ofrelatively little use in the muddy waters of the Ganges River,The relations of the basicranial bones suggest that the rostrum andbrain case have been telescoped together to a greater extent than inother river jDorpoises. To recapitulate the evidence in favor of thisobservation it might be pointed out that in correlation with the ros-trum being depressed below the brain case, the nasal passages havemoved backward and are situated on a level with the enterior mar-gins of the squamosals, the internal and external pterygoids extendforward to the level of the maxillary notches and thus entirely con-ceal the palatines, the opening for the infraorbital canal is withinthe temporal fossa, the zygoma is in contact with the supraorbitalprocess of the frontal, the antero-posterior diameter of the supra-orbital process of the frontal has been shortened and the process asa whole deflected obliquely forward as would be expected to resultfrom a lowering of the rostrum, and the lachrymal has been pushedinward and its posterior projection has been wedged into the maxillainstead of being inserted between the maxilla and the supraorbitalprocess of the frontal as in Lipotes. In skulls of Lipotes and Inia,the postpalatal axis bends downward from the axis of the rosrrumwhile both axes of the Platanista skull lie in approximately the sameplane.Although there seems to be great diversity of opinion as expressedin the published writings of many investigators regarding the alloca-tion of the genus Platanista^ the majority agree that this genus bearssome relationship to Iiiia and Lipotes. Of course, one can onlysurmise the incipient modifications which marked the development ofthose types of porpoise skulls we now know either fossil or living.In cases of the river porpoises, practically nothing is known abouttheir past geological history. Among the living forms, Platanistamay represent the most highly specialized type. The architectureof the Platanista skull in the region around the palatines, as shownabove, is singularly modified in comparison with the conditions foundin Phocaena. Skulls of Lipotes and Inia represent advanced stagesof another type of cranial architecture. The basicranium of the Zar-hachis slnill closely conforms with that of Platanista^ but the generalarchitecture of the dorsal face of the skull and rostrum agrees withthat of Lipotes. No comparisons can be made with Eoplatanista Dal
10 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 63,Piaz because the extremities of the supraorbital processes are missingand the cranium is very imperfectly preserved.Whenever forms which are manifestly different from each otheras regards certain structures are associated together within limitedgroups, it follows that such forms should possess some fundamentalstructures in common. Here again difficulties are obvious for eachinvestigator naturally holds that the structures with which he is mostfamiliar are fundamental. Usually, it is merelj^ a question of therelative importance to be attributed to each set of structural pecu-
, liarities and what gi'oup or groups of forms will best elucidate theparticular features which each investigator considers most important.In the opinion of the writer, fundamental structures are to be foundin the periotic and tympanic bones of the Cetacea. In view of thepeculiar combinations of characters which are found in the above-mentioned genera and the general similarity of the earbones, it ap-pears that Zarhachis represents one line, Platanista a second line, andInia or Lipotes a third line of a common ancestral stock.
Dorsal view.?The general arrangement of the elements compris-ing the dorsal portion of this fossil skull (pi. 1) is similar to that ofLipotes vexillifer.^ The differential characters of the present speciesare shown by the extremely long attenuate rostrum and the accom-panjdng elongation of the ankylosed symphj^sis of the mandibles,the prolongation of the zygomatic process of the squamosal and ofthe postorbital portion of the supraorbital process of the frontal sothat there is actual contact between them, and the absence of anelevated vertex.The long, flattened, and attenuated rostrum comprises more thanfive-sixths of the total length of the skull and is neither bowed up-ward nor bent downward. Anterior to the premaxillary foramina,the premaxillse are thick and convex; they decrease in width and inheight toward the tip of the rostrum. If the homologies of the bonesforming the tip of the rostrum are correctly understood, then thepremaxilla extends forward beyond the maxilla as a wedge-shapedsplint which is closely appressed to the large recurved front tooth.A small V-shaped indentation (15 mm. long and 6.5 mm. broadanteriorly) separates the two premaxillae at the tip of the rostrum;this indentation leads to a small canal which presumably representsthe roofed over mesorostral gutter.The inner margins of the premaxillae become closely appressed toone another at a point 165 mm. in front of the maxillary notches
^ Miller, G. S., Jr., A new river dolphin from China. Smiths. Misc. Coll., vol. 68.No. 9, Publ. 2486, pp. 1-11, pis. 2, 4, 6, Washington, 1918.
MARYLAND TOSSIL PORPOISE KEULOGG. 11and continue in contact to the apex of the above-mentioned indenta-tion at the tip of the rostrum. The premaxillae thus completely roofover the mesorostral gutter throughout most of its length. Theydiverge posteriorly and commence to spread apart, as remarkedabove, at a point 165 mm. anterior to the maxillary notches. Themesorostral channel is thus exposed for a distance of 160 mm. infront of the anterior end of the presphenoid. The raised convexportions of the premaxillae are widest just anterior to the pre-maxillary foramina and taper rapidly as they approach the levelof the nasal passages, and disappear slightly posterior to the supra-orbital processes of the frontals.There are three pair of foramina on the distal one-third of therostrum. No trace of similar foramina can be found in the skullof Lipotes^ though they are present in Inia^ but are irregularlyplaced and are found as far back as the maxillary notches. Sincetliese foramina are present in pairs, measurements were taken andtheir relative positions are shown in the following table:Position of the Paired Foramina near tip of Rostrum.
12 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63.overhanging premaxillae, this interpretation is based solely on theshort interval of mesorostral gutter exposed in front of the pre-sphenoid. In this region the vomer forms the floor of the gutter andtakes part in the formation of the lateral walls. If any reliance canbe placed upon the anterior limit of the exposed vomer as seen fromthe ventral view of the rostrum and upon analogous relations of thesame element in the skull of Lipotes^ then the vomer disappearsin the floor of the mesorostral gutter about 240 mm. in front of themaxillary notches. It appears that the vomer contributes thegreater part of either wall of the mesorostral gutter in front of thepresjDhenoid, but the corresponding surfaces of vomer and premax-illae are so smoothly mortised into one another that the actual lineof contact can not be determined with any degree of accuracy. Itis evident, however, that the contact between the vomer and eitherpremaxilla has its posterior limit near the anterior end of the pre-sphenoid. The dorsal margins of the mesorostral gutter are formedby thin plates of the premaxillae which project inward from theraised convex outer portions and whose edges are deflected obliquelyupward.The premaxillae do not closely approximate each other above thepresphenoid to form a slit-like anterior border for the nasal aper-tures as in Li'potes. In consequence most of the anterior end of thepresphenoid is visible. This porous bone forms a plug across theproximal end of the mesorostral gutter and rises to the level of tli3premaxillae above. In this last-mentioned feature, however, theskull of this fossil porpoise agrees more closely with Lipotcs thanwith Inia.All of the brain case posterior to the nasal passages, with the ex-ception of a small portion which comprises the vertex, was missingwhen the skull was excavated. Unfortunately the ascending por-tion of the mesethmoid also has been largely destro3^ed. The smallfragments of this bone which still adhere to the dorsal surface ofthe presphenoid show that the mesethmoid forms the partition sep-arating the nasal passages superiorly. Both nasal passages of thisfossil skull are well preserved and one is thus permitted to de-scribe these structures in considerable detail. After a most thoroughcomparison with Platanista, Lipotes, and /ma, it was found thatthe relations of the various elements which enter into the forma-tion of these passages are essentially the same in all. The m?seth-moid sheathes or forms a thin veneer of bone around the dorsalface and the upper halves of the lateral faces of the presphenoid,conceals the frontal fontanelle, and extends downward in eithernasal passage to meet the ascending process of the vomer. On thebase of the skull the vomer extends backward across the basisphenoid.
ART. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 13Hence the vomer sheathes the ventral face of the presphenoid andextends upward on either lateral face to meet the descending proc-esses of the mesethmoid. Thus the mesethmoid and the vomer linethe internal walls of the nasal passages. Ventrally, the posterior,the external, and the lower portion of the anterior wall of eithernasal passage are formed by the internal pterygoids. Each internalpterygoid is in contact posteriorly with the vomer and anteriorlywith the ascending process of the palatine. The anterior wall ofeither nasal passage superiorly is thus formed by the ascendingprocess of the palatine externally and by the posterior margin ofthe maxilla internally. The premaxilla contributes the upperniostportion of the anterior wall and limits the dorsal extension of theascending process of the palatine. As remarked above, the internalpterygoid curves around the nasal passage and establishes the lowerboundary of the passage.It is difficult to determine whether or not the back of this skulloriginally resembled Lijmtes although the curvature of the maxillaeas far as preserved suggests that the dorsal surface of this skullmust have conformed to that type of cranium. If our interpretationsare correct the temporal fossae were roofed over to a large extentby the frontal plates of the maxillae. The maxillae increase inwidth from the tip of the rostrum posteriorly; they attain theirgreatest width behind the orbit. When the maxillae reach themaxillary notches they push back over the frontals and expandlaterally to form the so-called frontal plates. The outer edge ofeither maxilla is turned abruptly upward and is closely appressed tothe internal face of the " up-ended " supraorbital process of thefrontal. This maxillary crest makes a right angle with the hori-zontal frontal plate of the maxilla; it terminates abruptly at theposterior end of the supraorbital process for the broken edges of thehorizontal frontal plate of the maxilla adhere to the base of thatprocess on the left side of the skull.The small fragment comprising the adjoining portions of thefrontals and supraoccipital represents all that is known of the backof the skull. This fragment is very important for it shows that thevertex of the skull was not strongly elevated or at least no prominentprotuberance, like in Inia or Lipotes, was present. It is also evi-dent that the maxillae were in contact with the supraoccipital andthat their internal margins overlapped the frontals on the vertex ofthe skull. The breadth of the combined frontals^ on the vertex isnarrower than the greatest distance between the outer walls of thenasal passages. The posterior end of the right nasal is present; Itis closely appressed to the frontal and apparently slopes obliquelyforward. From this it appears that the elevation of the vertex ofthe skull in Inia and Lipotes has been accompanied by the nasals5506?24?Proc.N.M. vol.03 16
14 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 63,
shifting to a vertical position and consequently becoming closely ap-pressed to that protuberance. If one attempts a restoration of theback of the skull by following the curvature suggested by thatfragment of the supraoccipital which is preserved, then the area be-tween the lambdoidal crests was higher than wide, but otherwisebore considerable resemblance to Inia.Lateral view.?A narrow rostrum equaling five times the lengthof the cranium, a large supraorbital process forming a high crestabove the orbit, a thickened zygomatic process of the squamosal, andthe absence of an elevated vertex, all contribute to the formation ofa skull (pi. 2) that is unlike either Lipotes., Inia^ or Platanista. Asin other long-beaked dolphins, the rostrum is formed mainly by theclosely joined maxillae and premaxillae, these elements being sup-ported internally by the anterior extension of the vomer. More thanhalf of the lateral aspect of the rostrum is formed by the maxilla.The premaxilla is shallower than the maxilla, decreasing in heightanteriorly and near the tip of the rostrum is barely visible from aside view. The axis of the rostrum is approximately straight. Inthis skull and in that of Lipotes the rostrum is noticeably broaderthan deep; this feature is more evident in the former than in thelatter. On the other hand the rostrum of the skull of Inia is rela-tively deeper throughout its length and appears to be bent down-ward.In this specimen the lambdoidal crests were apparently the highestpoints of the dorsal profile ; in front of these the maxillae slope for-ward to the rostrum. The skull as a whole is very slender, and theheight at the vertex is proportionately low in comparison with thatof the base of the rostrum. The alveolar gutter is visible throughoutits length from a side view and terminates 118 mm. in advance of themaxillary notch. The temporal fossa as restored is relatively smalland equals about twice the length of the orbit.Above the orbit the supraorbital process of the frontal is bentabruptly upward and forms a vertical crest. The maxilla also bendsupward and sheathes the internal face of this crest ; the external mar-gin of the maxilla bends over and is closely appressed to the anteriorand dorsal faces. The greatest vertical depth of the left supraorbitalprocess of the frontal is 81 mm., and the greatest length is 105 mm.The crestlike portion of the supraorbital process is reduced to a merevestige in Lipotes^ Inia, and Platanista.The external face of the supraorbital process slopes obliquely up-ward and inward. It is " fan-shaped " in outline, the anterior anddorsal margins being evenly rounded, while the posterior marginis nearly straight, and the ventral margin is emarginate. Pos-teriorly, the supraorbital process is drawn out into a narrow post-orbital projection which slopes downward ; it thus comes in contact
ABT. 14. MARYLAND FOSSIL PORPOISE?KEIJ:,OGG. 15
with the zygomatic process of the squamosal and is closely appressedto that bone. The postorbital projection is exceedingly long in Iniaand slightly shorter in Lipotes^ but does not extend backward to thezygoma in either of these genera. On skulls of Inia and Lipotes, thelachrymal is closely appressed to the anterior face of the supraorbitalprocess. The lachrymal and ankylosed jugal are missing on the leftside of this fossil skull. Originally the lachrymal must have beeninserted between the overlapping maxilla and the anterior face of thesupraorbital process, as will be shown in another part of this de-scription.The zygomatic process of the squamosal is greatly thickened dorso-ventrally in contrast to the long attenuate zygoma of Inia andLipotes. As a whole the zygoma is robust, curved, and rather short;the dorsal surface curves gradually forward and upward. Theposterior margin of zygoma is nearly straight and forms an obtuseangle with the axis of the rostrum. Correlated with this differenceis the form of the glenoid cavity and the postglenoid process. Thelatter is relatively thin, directed backward and downward. Thegreatest length of the zygomatic process along the glenoid face is99 mm. and the greatest depth is 63 mm. On the whole the zygomabears a much closer resemblance to Eoplatanista italica Dal Piaz ?than to any living river dolphin.Ventral view.?The ventral surface of the rostrum (pi. 1) isformed almost entirely by the maxillae which meet mesally in alinear suture in front of the vomer, and extending forward paralleleach other throughout the distal three-fourths of the rostrum. Allof the teeth in either tooth row are lodged entirely in the maxillae.The maxillae broaden from the tip of the rostrum to the maxillarynotches. The rostrum is not narrowed between the tooth rows andthe maxillary notches as in Lipotes. The lateral borders of the max-illae establish the margins of the rostrum and posterior to the toothrows these margins are thin and bladelike. The rostrum is eniar-ginate at the tip, the sides of the notch being formed by the pre-maxillae, small splintlike processes of which extend forward be-yond the maxillae. On either side the premaxillae are not visiblefrom a ventfal view posterior to the first tooth. Posteriorly, as re-marked above, the maxillae separate to allow the keel of the vomerto appear between them. This keel of the vomer is continued back-ward, and increasing in height, attains its maximum depth at nasalpassages and then abruptly subsides.Posteriorly the maxillae are overlain by the external pterygoids.Near the proximal end and in a middle line each maxilla comes in
? Dal Piaz, G., Gli odontoceti del Miocene Belluiiese. Parte Quarta. EoplatanistaItalica. Memorie dell'Istituto Gcclogica delJa R. Universita di Padova, vol. 5, pi. 1,tig. 1, 1916.
16 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63.
contact with the internal pterygoid, a flattened wedge-like bone whichis in contact externally with the external peterygoid. The openingfor the infraorbital canal appears in the maxillary bone in front ofthe nasal passages but posterior to the maxillary notch.On the ventral surface of the skull the vomer surrounds the pre-phenoid and entirely conceals it from view. It extends backwardacross the basisphenoid, but, since the basicranial portion of thisskull is missing, the posterior limit can not be determined. Thevomer is deepest at the nasal passages and in consequence this por-tion of the skull is characterized by a prominent keel. This keelincreases in height posteriorly and attains its greatest depth imme-diately in front of the nasal passages; it flattens out anteriorly atthe level of the last tooth. The concave areas on the maxilla on eitherside of this keel extend forward to the tooth rows, while in Lipofesthey terminate 155 mm, posterior to the tooth roAvs.The peculiar features and modifications of the bones surroundingthe above-described keel may be compared with PJatanista andLipotes. Unfortunately, some uncertainty exists as to whether ornot the type skull of the Chinese river dolphin ^ has been damaged.The irregular edges of the descending plates or fortuitous projectionsof the maxillae indicate that part of these bones are missing. If theywere complete, they would inclose pyramidal cavities similar to thosepossessed by this fossil skull. The relations between the vomer, theinternal pterygoids, and the palatines are essentially the same inall three genera. It should be noted that the maxillae of PJatanistaand Lipotes meet mesially in a linear suture at level of last toothand thus conceal the keel of the vomer in front of the nasal passages.In this fossil porpoise the keel of the vomer appears between themaxillae.On the left side of this fossil skull (pi. 2) the external pterygoidextends forward 112 mm. in advance of the posterior wall of thenasal passage. This bone also extends backward beyond the nasalpassage; it is bounded by the maxilla anteriorly, by the squamosalposteriorly, and by the frontal superiorly. In these respects theapproach is directly toward the relations existing between thesebones in the skull of PJatanista (pi. 6). One of the distinguishingfeatures of skulls of PJatanista and of this fossil porpoise, as com-pared with skulls of Lipotes and Inia, is the expansion of the ex-ternal pterygoid. In consequence the alisphenoid is not exposed onthe side of the skull in the temporal fossa.
'Miller, G. S., jr., A new river dolphin from Cliina. Smithsonian Misc. Coil., vol. 68.No. 9, Publ. 2486. pi. 6, Washington, 1918.
ART. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 17In Platanista^ the palatines are entirely concealed by the overlyingexternal and internal pterygoids; the latter extend forward to thelevel of the preorbital projection of the supraorbital process. Tlievaginal plate of the internal pterygoid is sutiirally united with thevomer posteriorly. The thin plate of the internal pterygoid curvesaround the nasal passage and meets the maxilla mesally; it thenturns abruptly and extends forward beneath the external pterygoid.That portion of the internal pterygoid which lies anterior to the nasalpassages is closely appressed to the palatine and the maxilla above;the external margin is fused with the corresponding margin of theexternal pterygoid. As a result a cavity is formed between theinternal and external pterygoids, the opening being along the keel.
"W-Tien the internal and external pterygoids are removed, the palatineis exposed (pi. 5). The peculiar position of the palatine has beenpointed out and discussed by Eschricht and Anderson. It has beenreduced to a small elongated bone whose antero-posterior diameteris about equal to the diameter of the corresponding nasal passage.The palatine is closely appressed to the maxilla and these two bonescombined form the anterior wall of either nasal passage. Wliilesimilar relations between the palatine, maxilla and internal ptery-goid are maintained in skulls of Lipotes and /?im, the palatine, how-ever, is not entirely concealed by the internal pterygoid.The similarities and differences obtaining between Platanista onone hand, and Lipotes and Inia on the other have been fully discussedabove. Detailed comparisons have shown that the relations of thevarious bones in the basicranium of this fossil skull are in agree-ment with Platanista. One detail could not be satisfactorily deter-mined from this fossil skull and that is the exact relations betweenthe internal pterygoid and the external pterygoid near their anteriorextremities.The thickened edge of each internal pterygoid appears in theinterval between the lower edge of the external pterygoid and thekeel of the vomer. Slit-like apertures appear on either side betweenthe keel of the vomer and the exposed edges of the internal ptery-goids. It is possible that these apertures may be the result of distor-tion brought about by crushing. The pyramidal cavity which isthus formed on ether side of the keel is bounded on the inside by theinternal pterygoid, on the outside by the external pterygoid, and atthe rear by that portion of the former which curves around the nasalpassage.After making careful comparisons between this fossil skull andthose of Lipotes and /ma, it was found that differences were observ-
18 PROCEEDINGS OF THE NATIONAL MUSEUM. voi.. o:?,
able in the size and relations of the various bones which comprise theouter wall of the cranium. In these details, however, the approachis directly toward the conditions existing in the skull of Platanista.In the latter, however, the position of the lachrymal with referenceto the inferior opening of the infraorbital canal is somewhat differ-ent. The squamosal is relatively large, but the internal portionwhich forms part of the outer wall of the cranial cavity is largelymissing. The lateral projection of the squamosal forms the forwardprojecting zygomatic process and the downward projecting postgle-noid process. The left zygomatic process is complete; its greatestwidth is 61.5 mm. and its greatest length is approximately 100 mm.As seen from the ventral view, the zygoma is robust and short incomparison with Inia. On the other hand, the zygoma bears a closeresemblance to that of Platanista and this similarity is accentuatedby the contact between it and the supraorbital process of the frontal.The glenoid surface extends forward upon the zygomatic process
;
it is rather wide, concave antero-posteriorly, and is limited externallyand anteriorly by a distinct outer margin. The external auditorymeatus, which commences at the postero-internal margin of thesquamosal, apparently, does not wind around the postglenoid processof that bone for no groove can be found. The postglenoid processis directed backward and downward and does not curve forward asin Lipotes. The posterior portion of the glenoid articular surfaceof the Chinese river dolphin skull is deeply concave ; in consequencethe articulation with the lower jaw is restricted to a narrow area.Such is not the case with this fossil skull, for this portion of theglenoid articular surface is almost flat. On the left squamosal atthe inner side of the glenoid area there is a shallow groove whichcommences behind the postglenoid process, but which does not ex-tend forward to the anterior margin of the glenoid process of thesquamosal as in Lipotes.The origin of or possible use for a peculiar shelf formed betweenthe upper margin of the squamosal and the frontal is difficult toexplain. A similar groove is present in the skull of a youngPlatanista (Cat. No. 172409, U. S. Nat. Mus.), but this structuredoes not occur in Inia or Lipotes. In this fossil skull the shelfand groove (pi. 4) formed by it extends forward to the anteriormargin of the supraorbital process of the frontal; it is thus boundedinferiorly by the squamosal and the external pterygoid. The grooveis much shorter in the Platanista skull and terminates anteriorlyat the level of apex of glenoid portion of squamosal; the foramenovale opens into this groove. In the left temporal fossa of this
AiiT. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 19fossil skull the external pterygoid comes in contact with thesquamosal and the maxilla; these two bones combined limit itsventral expansion. Posteriorly, the external pterygoid sends aprocess forward and upward to meet the frontal.Certain foramina are present in the skull of Platanista which areapparently absent in this fossil skull. No information regardingthese foramina can be secured from the right side of the craniumfor it has been completely destroyed, and the imperfect preservationof the left side may possibly explain the failure to identify theseforamina there. Between the external pterygoid and the frontalthere is a small opening which may represent the sphenorbitalfissure.The lachrymal is missing completely on the left side of the skull,but fragments of this bone are present on the right side. A smallfragment of the lachrymal is wedged in between the maxilla andthe right supraorbital process of the frontal ; a horizontal, flattened,proximal piece must have filled in the space between the anteriormargin of the frontal and the ventral plate of the maxilla. On theleft maxilla and internal to the maxillary notch three obliquegrooves are plainty visible. These grooves represent the sutures forthe jugal which in turn was ankylosed to the lachrymal, as will beshown below. These three features show that the lachrymal whencomplete must have maintained approximately the same relationswith the surrounding bones as exist in the skull of Lipotes.In the skull of Liyotes^ the lachrymal is an elongate bone whichcommences internally behind the opening for the infraorbital canal,and occupies the interval between the frontal and the ventral plateof the maxilla. It extends outward and its distal extremity isclosely appressed to the anterior face of the supraorbital processof the frontal. The lachrymal thus forms the outer margin for theso-called maxillary notch. The jugal is fused with the lachrymaland is suturally united to the maxilla at the maxillary notch. It isthus evident that the skull of the living genus Lipotes and that ofthis fossil porpoise possess lachrymals which are essentially thesame both in shape and in relation to the surrounding bones. Itshould be noted, however, that in this fossil skull the outer marginof the maxillary notch is formed entirely by the maxilla. The distaJend of the lachrymal is very thin and is merely a wedge betweenthe anterior face of the supraorbital process of the frontal and themaxilla.
20 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63,3Ieasurements of the skull. mm.Total length (estimated) 1,195.Length of rostrum (maxillary notches to tip of beak) 1,000.Breadth of skull across zygomatic processes of squamosals 268.Height of skull (basisplienoid to vertex, estimated) 122.Height of rostrum at level of maxillary notches 80.Total length of maxilla (estimated) 1,125.Greatest breadth of right premaxilla in front of nares 42.Greatest breadth of left premaxilla at maxillary notch 37. 5Breadth of rostrum at maxillary notches 155.Breadth of rostrum at proximal end of alveolar rows 98.Breadth of rostrum at extremity 25.Distance between inner margins of maxillae on vertex 28. 3Greatest breadth of left supraorbital process of the frontal 105.Greatest dorso-ventral depth of left supraorbital process of frontal 81.Greatest breadth of braincase between temporal fossae (estimated) 106.Length of exposed frontals on vertex 42.Breadth of exposed frontals on vertex 23.Length of right zygoma_^ 100.PERIOTIC.In general appearance the periotic of this fossil porpoise agreesmore closely with Platmiista gangetica (Cat. No. 23456, U. S. Nat.Mus.) than with Inia geojfrensis (Cat. No. 49582, U. S. Nat. Mus.)It is not distinguished from that of Platanista by any sharplymarked features other than the possession of a larger fenestra ovalis,a more elongated internal acoustic meatus, and a wider interval be-tween the foramen singulare and the cerebral orifice of the facialcanal.The posterior process is missing as the periotic is broken just pos-terior to the fenestra ovalis. In case of some of the living dolphinsthe posterior process is frequently damaged when an attempt is madeto remove the periotic bone from the skull and the destruction of theback of the cranium maj^ account for the loss of the posterior proc-ess of the periotic of this fossil porpoise. The internal and centralportion of the periotic represents the pars cochlearis. As a whole,this structure is obliquely compressed dorso-ventrally and is lessconvex than that of either Platanista or Inia; the posterior portion isslightly elevated. The fenestra rotundum is large, and internallya thin partition of bone separates it from the scala vestihnU. Acrescentic fissure following the course of the scala vestihvli is presenton the internal margin of this partition and this also correspondsin its position to that of Platanista. In this periotic the fenestrarotundum is more or less ovoidal in outline, but in a second specimenthe orifice is distinctly circular. The posterior face of the parscochlearis is rather abruptly truncated above the fenestra rotundum.
AKT. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 21The fenestra ovalis is relatively much larger than in Platanista,oval in outline, and extends downward upon the lateral face of theperiotic. No stapes is present and it is evident that this element didnot completely fill the fenestra ovalis with its foot plate. In thisfeature also this periotic agrees with Platanista, for in the latterthe foot plate of the stapes is held in position by an annular liga-ment. The foot plate of the stapes completely fills the fenestraovalis in the periotic of Inia and is firmly lodged. The groove forfacial nerve leads directh' to the epitj^mpanic orifice of the facialcanal as in I?ila and thus differs from the type of groove present inPlatanista. Only that portion of the fossa for the stapedial musclewhich extends downward on the external face of the pars cochlearisis preserved on this periotic, the remainder having occupied theprocess which is missing. A characteristic feature of the tympanicface of this periotic is the large swollen tuberosity on the anteriorprocess. The fossa for lodging the head of the malleus is large, rec-tangular in outline, and situated in the same relative position as inPlatanista and Inia^ but extends inward beyond the epi-tympanicorifice of the facial canal. A rather deep but narrow groove for theexternal auditory tube appears to have been present between theabove-mentioned tuberosity and the posterior process. The anteriorend of the fossa incudis is present.The anterior process is rather long and is directed obliquely in-ward; it is thickened dorso-ventrally and compressed laterally, butits ventral and dorsal surfaces are curved and form a bluntly pointedapex at the antero-ventral angle. On the external face of the ante-rior process is a deep V-shaped groove or crease. An elongate con-cave articular facet occupies a considerable portion of the ventralface of the anterior process; this facet supports the outer lip of thetympanic bone. It is possible for the uncinate process or accessoryossicle of the tympanic bulla to curve around the posterior face ofthe anterior process of the periotic (pi. 7, fig. 6), paralleling condi-tions present in that of Platanista (pi. 7, fig. 5) and thus differingfrom that of Inia. In the last mentioned genus the accessor}^ ossi-cle is lodged in a depression in front of the fossa for the head ofthe malleus.The resemblance between the periotic of this fossil porpoise andthat of Platanista is even more striking when these bones are viewedfrom the cerebral side. The tractus spiralis foraminosus^ the cere-bral orifice of the facial canal, and the foramen singulare ail lieM'ithin a common fossa, which is compressed anteriorly and pyri-form in general outline. The tra.ctus spiralis foraminosus is welldefined and ac the end of the spiral is the foramen centrale. An-terior and internal to the tractus spiralis foraminosus is the cere-
22 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63,bral orifice of the facial canal. The position of the foramen singu-lare corresponds more closely with Inia than with Platanista. Inthe latter, the foramen singulare is present as a minnte opening onthe posterior wall of the facial canal. In the periotic of this fossilporpoise, the foramen singulare is situated relatively nearer to thespiral tract although a low partition separates these structures. Thecerebral orifice of the aquaeductus vestihuli is of moderate size andelongate; the orifice is situated external and slightly posterior tothe internal acoustic meatus as in Platanista. A narrow isthmus ofbone lies between the cerebral orifice of the aquaeductus cochleae andthe fenestra rotundum; the canal is relatively large. In both Iniaand Platanista the aquaeductus cochleae and its cerebral orifice arevery minute. The cerebral orifice of the aquaeduct of the cochleain this fossil periotic is situated 2.6 mm. from the internal acousticmeatus and at least 4.5 mm. from the same orifice of the aquaeduc-tus vestihuli. The 'pars vestibula7is is relatively small, with the ex-posed faces rounded, and largely concealed ventrally by the processeswhich arise from it.Measurements of the periotic hone. mm.Greatest length of periotic (tip of anterior process to broken posteriormargin) 33. 5Greatest depth of labyrinthic region of the periotic 11. 5Greatest breadth of labyrinthio region of the periotic 19.5TYMPAXIC.Neither one of these two tympanies is entire. The thin brittleouter lip which arches over the involucrum and the slender processeswhich project from it are frequently damaged when the tympanic isbroken away from the periotic, even in case of the living purpoises.Since the processes which join the tympanic to the periotic are veryslender, one may expect to find many broken and otherwise imperfecttympanic bones.The left tympanic is badly broken, and some of the missing pieceswere not found in the matrix. The fragments which were found havebeen fitted together (pi. 7, fig. 2), but no restoration has been at-tempted. Comparisons were made with the tympanic bones of some20 genera of living dolphins and only 1 genus, Platanista (pi.7, fig. 1), exhibited any marked agreement. The tympanic bones ofthis fossil porpoise and Platanista are very similar in general fea-tures, even to the matter of size. Ajnong the other living dolphinsavailable for comparison, Inia showed the closest approach to thistype of tympanic. It is unfortunate that the type skull of Lipotesvexillifer lacks both tympanic and periotic bones.
JVKT. 14. MARYLAND FOSSIL PORPOISE?KELLOGG. 23Although imperfect, the left tympanic bone of this fossil porpoiseis sufficiently entire to show the size and direction of the anterioroutlet or the tympanic aperture of the eustachian canal. The an-terior end of the tympanic is drawn out into a narrow laterally com-pressed process which is directed forward and downward. Thisprocess is missing on the right tympanic (pi. 7, fig. 4), but the thinouter lip is practically entire. In Platanista (pi. 7, fig. 3) theinferior margin of the outer lip of the bulla turns abruptly andcurves inward, forming a shelf. This modification, apparently, wasnot present on the tympanic of this fossil porpoise.The tympanic cavity, which is bounded by the overarching outerlip and by the involucrum, is essentially similar to that of Platanista.The anterior process of the tympanic, which unites with the peri otic,is broken off at the level of the outer lip. When viewed from theexternal side, the posterior margin of the tympanic is seen to be morerounded than in Platanista^ the processus sigmoideus is longer, andthe tympanic as a whole is relatively deeper. The processus sig-moideus of the right tympanic (pi. 8, fig. 2) is entire, the terminalhalf being twisted at right angles to the basal. The groove on theexternal face of the tympanic anterior to the processus sigmoideusis relatively broader than in Platanista (pi. 8, fig. 1). The so-calledposterior conical apophysis is shorter than in Platanista, but other-wise the relations between this apophysis and the processus sig-
-moideus are essentially the same in both genera. The apophysisprojects above the level of the superior face of the involucrum.The posterior process (pi. 7, fig. 2) is broken off at the level of theinvolucrum. The broken edges show that it projected from the pos-terior end of the tympanic and that the out?r lip and the involucrumcontributed to its formation as in Platanista. The thick convexinvoluted portion of the tympanic is slightly and unequally de-pressed below the level of the overarching outer lip and subsidesrather abruptly just posterior to level of the anterior process of theouter lip, while the anterior portion becomes decidedly concave in-ternally. The surface of the thickened or posterior portion of theinvolucrum is constricted or depressed medially on its internal anddorsal faces.The ventral surface of the tympanic exhibits a deep groove whichis most pronounced near the posterior margin. In Platanista (pi.8, fig. 3), however, this groove is not open, but is filled in withspongy bone. When viewed from the ventral side the outer marginof the bulla (pi. 8, fig. 4) is seen to be biconvex and much broaderanteriorly than in Platanista. The anterior and posterior marginsof the bulla do not slope as strongly from the external to internalfaces as they do in the living genus.
24 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63,In regard to the slight differences which are observable in thetympanic and periotic bones of this fossil porpoise and Platanista^one is encouraged to conclude that there must be a closer relationshipexisting between these dolphins than v/ith the Delphinidae.Measurements of the tympanic. mm.Greatest length of left tympanic bulla 52. 5Gi'eatest width of right tympanic bulla 27.6Greatest depth of right tympanic bulla on internal side 20Greatest depth of right tympanic bulla on external side (ventral face totip of processus sigmoidcus 36.5MANDIBLES.One distinguishing feature of the combined lower jaws (pi. 3) ofthis fossil porpoise, as compared with jaws of Platanista, Inia, andLipofes, is the great length of the symphysis. The free portion ofeither mandible is less than one-third of its total length. The com-bined lower jaws taper toward the tip, the width at the proximal endof the symphysis being equal to more than four times the width atextremity. The depth of either mandible at proximal end of thesymphysis is nearly three times that at the extremity. There is aconspicuous median longitudinal groove between the tooth rows onthe posterior one-half of the symphysis. The distance from the sym-physis to last tooth is much less than distance between same tooth ofopposite rows.Back of the symphysis the ramus consists mainly of a thin shellof bone. The external wall of the ramus is continued backward toform the coronoid process, the condyle, and the angle. The internalwall of the right ramus terminates 183 mm. behind the symphysis;at this point the inferior dental canal enters the mandible. Betweenthe symphysis and the terminus of the internal wall the ramus ishollow ; the depth of the cavity at the proximal end as estimated isequal to approximatelj^ four times that at the symphysis.The superior margin of the mandible gradually rises from thesymphysis to the coronoid, and is accompanied by a downward cur-vature of .the inferior margin. In consequence the coronoid as origi-nally preserved was deep and somewhat convex on the external face.As a result of crushing, the posterior one-third of both mandiblesshow a longitudinal fracture at the level of the condyle. The lowerportions of each of these mandibles as shown on plate 3 are thuspushed inward and lie in a horizontal position. For this reasonsome allowance must be made in estimating the depth of the mandi-ble at the coronoid. It appears that the depth through the coronoid(135 mm. estimate) is equal to less than one-half of the free portionof the left mandible. The coronoid is broadly rounded, while the
ART. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 25
angle is abruptly truncated. The condyle is large, flattened, andslopes obliquely backward ; the external margin projects laterally be-yond the plane of the coronoid.When viewed from the ventral side (pi. 3) the symphysial regionis seen to be much broader than that of Lipotes. A pair of longi-tudinal grooves incloses a raised ridge which diminishes inheight and in width anteriorly. Eight or more foramina open intoeach of these grooves. The grooves extend forward to the tip ofthe symphysis, but on the distal 75 mm. they are reduced to verynarrow channels. Posteriorly, they extend backward a short dis-tance beyond the symphysis.Measurements of the mandibles. mm.Length of right mandible (condyle to tip) 1,097.0Length of left mandible (condyle to tip) 1, 120.Greatest breadth of combined mandibles at extremity 18.Greatest depth of combined mandibles at extremity 9. 3Greatest breadth of combined mandibles at proximal end of symphysis- 90.Greatest depth of combined mandibles at proximal end of symphysis
?
27.Greatest depth of right mandible at level of proximal alveolus 21. 5Greatest depth of left mandible at level of proximal alveolus 21. 7Greatest length of ankylosed symphysial portion of ramus 803.Length of right alveolar row 820.0Length of left alveolar row 845.0Depth of mandible at coronoid (estimated) 135.0Depth of condyle of left mandible 45.
The anteriormost pair of teeth on the rostrum is considerablylarger than any of the following teeth, but the form of the crown andthe character of the enamel are essentially the same in all of theteeth preserved. Nineteen teeth are in place on the right side of therostrum. Of the mandibular teeth 13 are in place on the right sideand 12 on the left side. The alveoli are distinct and anteriorly arearranged in pairs. The alveoli number 87 on the right side and 8Gon the left side of the rostrum; 70 alveoli are present on the rightand 72 on the left mandible.The total number of teeth present originally was about 315, ofwhich 45 or about one-ninth are preserved. This fossil skull possessedmore than twice as many teeth as an average Platanista skull ; theanterior teeth are relatively shorter than the same teeth of Platanistaand all project strongly beyond the sides of the rostrum and lowerjaws. The teeth of Lipotes project to some extent beyond the sidesof the rostrum and mandibles, more so than in Inia., but not sostrongly as in this fossil skull. The anterior teeth of this fossil skullare noticeably larger and longer than the posterior teeth. The second
26 PROCEEDINGS OF THE NATIONAL MUSEUM. voi.. 03.Icoth on the left side possesses the longest enamel crown (10 mm.),while the first tooth on the right side has the broadest crown (5 mm.).The smallest tooth has an enamel crown 7 mm. long and a maxi-mum diameter of 3 mm.Skulls of Lifotes and Inia possess teeth whose enamel crowns arestrongly rugose. The surfaces of the enamel crowns of these fossilteeth are ornamented with fine longitudinal striae ; those of a youngPlatanista skull are smooth. In case of old individuals of Platanistathe enamel crowns of the teeth almost always show the effects of wearand on many of the teeth the enamel is entirely missing. The crownscf the teeth of this fossil porpoise and those of Platanista are com-pressed antero-posteriorly. There is no well defined neck between theexpanded portion of the root and the enamel crown. The swollenpart of the root of many of the teeth has a greater diameter thanthat of the crown. There is no indication of a cingulum. The distalextremities of the roots are slender, elongated, and curved backward.The mandibular teeth are similar to the maxillary teeth in form, butthe crowns of the posterior teeth are relatively smaller. ?HYOID BONES.The hyoid bones bear some resemblance to those of the Delphinidae,especially Phoeaena. Although the basihyal and the two thyrohyalsare ankylosed (pi. 9, fig. 1), the sutures between the component partsare apparent. The central portion (basihyal) is strongly compresseddorso-ventrally and possesses two short, anterior, conical projections(ceratohyals) which were joined in front by cartilage with the elon-gate stylohyals. The expanded lateral wings (thyrohyals) of thehyoid bone curve backward and upward, but their distal ends arebent downward. These thyrohyals are subcrescentic in outline, rela-
? ively thin, concave superiorly, and convex inferiorly. Internallythere is a slight elevation or ridge which marks the line of fusion ofthyrohyal with the basihyal. The antero-external margin of eitherthyrohyal is recurved and to it were attached the stylohyoid liga-ments.The ankylosed basihyal and the two thyrohyals of this fossil por-poise are similar in some respects to those of Inia geojfrensis. Theydiffer widely from the figure given by Anderson^ for those of Plata-nista^ which shows the thyrohyals dilated at their basihyal endsinstead of mesially, the presence of free elongate rodlike ceratohyals,and the absence of posterior projections on the basihyal. Small pos-terior projections are present on the basihyal of this fossil hyoid.
s Andeison, J., Anatomical and Zoological Researches: Comprising an account of theZoological Results of the Two Expeditions to Western Yunnan in 186S and 1875. Lon-don (1878), p. 528 pi. 40, fig. 20. 1879.
ART. 14. MARYLAND FOSSIL POEPOISE KELLOGG. 27The stylohyals (pi. 9, figs. 2-3) are decidedly more like those ofInia than those of Platanista. Each is an irregular elongate bone,slightly curved upward and suddenly curving forward at the distalend. The anterior edge for its greater part is rounded and theposterior margin compressed so that a cross section of the stylohyalwould be somewhat ovoidal. These bones are ^arly a third againas long and twice wider than are the flattened stylohyals of Iniageojfrensis. Measurements of the hyoid hones. mm.Greatest length of central portion (basihyal) 36.0Antero-posterior width across ceratohyals (outside measurement) 36.5Greatest thickness of thyrohyal at distal end 9.0Greatest breadth of thyrohyal 49.0Greatest length of thyrohyal (postero-internal margin to tip) 107.5Greatest length of left stylohyal 153. 5Greatest breadth of left stylohyal 21. 5CERVICAL VERTEBRA.All of the cervical vertebrae except the atlas are missing. Theatlas is complete and agrees in some respects with the cervical de-scribed by Cope and by Case ? as Priscodelphinus grandaevus^ but ismuch larger. While agreeing with the atlas of Inia geojfrensis inthe presence of both upper and lower transverse processes, it differsin many details of form, some of which may be attributed possiblyto individual variation. The atlases of Liyotes and Platanista havelost the upper transverse process (diapophysis) and the lower one(parapophysis) is considerably shorter. In the living river dolphinsa free atlas is accompanied by separated cervicals.This fossil atlas is relatively deep antero-posteriorty, the length(66 mm.) being about one-half of the greatest breadth (113.5 mm.)across the anterior articular facets. The facets for the occipitalcondyles (pi. 12, fig. 4) are concave, broader above than below, andinclined obliquely outward. They are separated inferiorly by arather wide interval (18 mm.). The neural arch is not stronglyelevated and is broad antero-posteriorly. On either side the neura-pophysis (pi. 8, fig. 5) is pierced by a large elliptical vertebra-arterial canal. The neural arch may have borne a low, blunt spinefor a longitudinal rugose area which appears to represent its baseis present.The upper and lower transverse processes project backward. Theupper transverse process is broad and flattened dorso-ventrally ; theposterior margin is rounded while the anterior is thin and blade-like.
3 Case, E. C, Miocene Text, Maryland Geol. Suiv., Baltimore, p. 15, pi. 12, figs, la,lb, Ic, 1904.
28 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63.On the dorsal surface of the upper transverse process and adjacentto the large canal is a depressed area. A small circular foramenconnects this area with the vertebrarterial canal, and may representthe foramen for the exit of the spinal nerve. The lower transverseprocess is rounded and attenuated.The posterior articular facets (pi. 12, fig. 3) for the axis areelongate with nearly straight vertical external margins and are in-distinctly set off from the posterior face of the centrum. Thehyapophysial process is short, thick, and irregularly pitted orroughened. Measurements of cervical vertebra (in millimeters).Greatest depth (vertically) of vertebra (tip of neural spine to inferiorface of centrum) 89.5Anterior breadth of spinal canal 53.5Median depth of spinal canal (anteriorly) 47.0Distance between tip of one lower transverse process (parapophysis)and tip of opposite one 121.0Greatest distance across vertebrae between outside margins of anteriorarticular facets 113. 5Greatest height of articular surface for condyle 53.2Greatest breadth of articular surface for condyle 30.0Distance across vertebra between tips of upper transverse processes(diapophyses). (Outside measurement) 131.0Greatest length of superior face (neurapophysis) of vertebra 37.5Greatest diameter of vertebrarterial canal 14.2Distance from anterior face (inferiorly) to tip of spinous process(posteriorly) 39.Greatest length of lateral face of vertebra 67. 5Distance from tip of upper transverse process (diapophysis) to tip oflower transverse process (parapophysis). (Outside measurement)? 64.0DORSAL VERTEBRAE. ^Comparisons have been made between this vertebral column (pi.10) and those of Inia (jeoffrensis (Cat. No. 49,582, U.S.N.M.) andPlatanista gangetica (Cat. No. 172,409, U.S.N.M.) Ten dorsalvertebrae are preserved and represent a continuous series. With theexception of the fourth dorsal (pi. 13, fig. 2) which lacks the an-terior epiphysis, all of them are practically complete. The dorsalsdiffer noticeably from those of Inia and to a less extent from thoseof Platanista. Unfortunately the only skeleton of Platanista avail-able for comparison belongs to a young individual. The vertebralcolumn of Inia includes thirteen dorsals and three lumbars whilethat of Platanista includes ten dorsals and eight lumbars. As re-marked above ten dorsals are known for this fossil porpoise and inaddition it possessed at least four lumbars.
Airr. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 29These dorsals differ noticeably from all the dorsal vertebrae de-scribed by Cope and Leidy, not only in size, but also in structure.They also differ from many recent delphinoids in that the neuralspines are nearly vertical instead of being strongly inclined back-ward or forward {Inia). In the first three dorsals the antero-posterior diameter of the spine at the tip is somewhat less than atthe base, this being especially noticeable in the first dorsal. Theneural spines of the remaining dorsals, however, are of approxi-mately the same depth throughout. In this respect they resemblethe dorsals of Plataiiista more closely than those of Inia or anyother recent species available for comparison.The anterior dorsal vertebra of this fossil porpoise presents themajority of those features which characterize the first dorsals ofInia geo-ffrensis and Platanista gangetica. This vertebra agrees withthat of Inia in the general appearance of the transverse process andthe position of the articular facet for the tuberculum of the first rib,but differs in the great depth of the centrum and the relative widthand height of the neural spine.The anterior dorsal is peculiar as regards the dimensions of thecentrum which is almost as long as broad. The epiphyses are rela-tively thin. There is a distinct oval facet for the accommodation ofthe head of the second rib on the postero-superior lateral margin ofthe centrum. The neural arch is low, broad, and thin, with a lateraltransverse process on each side which bears an articular facet forthe accommodation of the tuberculum of the first rib. The articularfacet on the transverse process for tubercle of rib is horizontal, thatis it is situated on the inferior face of this process. If any reliancecan be placed on the position of this articular facet, then this is actu-ally the first vertebra of the dorsal series.Compared with the same vertebra in a young Platanista skeleton,the principal differences are as follows: The centrum is longer, butnot so compressed dorso-ventrally ; the neural canal is much larger
;
and the posterior margin of the neural spine is more arcuate.In this fossil series of dorsals, the centra increase perceptibly inlength from the firet to the last. The prezygapophysial facets of thefirst six dorsals are nearly horizontal in position while those of thelast four (pi. 13, fig. 1) are oblique. In the first six dorsals thearticular surface for the accommodation of the postzygapophysis iscircular; in the others this surface is nearly oval. These facets forthe postzygapophyses (pi. 13, fig. 2) are situated on the superior faceof the upturned margin of the laminae in front of and below thepoint where the metapophyses arise. As we go backward along theseries they gradually shift from a horizontal to a lateral position.5596?24?rroc.N.M.vol.63 17
30 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. r,3.The prezygapophysial facets are wider apart and are more divergentthan tlie postzygapophysial facets (pi. 14, fig. 2). The metapophysesproject beyond the epiphyses of the centrum throughout the serieswhile in the case of the postzygapophyses, with the exception of thefirst four dorsals, such is not the case. The metapophyses alsorapidly increase in size from the seventh to the tenth dorsals andbeginning with the seventh dorsal project obliquely upward.The second and third dorsals are very similar in appearance tothe first. The most apparent differences are the increase in distalwidth of the neural spines and the shifting of the articular facetfor tubercle of rib to a more lateral position on the transverse process.The fourth (pi. 13, fig. 3), fifth, and sixth dorsals possess deepneural spines and their anterior and posterior margins are slightlycurved. The transverse processes are well developed and projectforward in the first six dorsals. Anteriorly they arise high up onthe neural arch and when followed back gradually shift theirposition on the vertebrae until on the tenth dorsal they projectfrom the middle of the centrum. On the tenth dorsal, the trans-verse process and its articular facet for the tuberculum of rib aredirected backward. The external face of the transverse process isdeeply excavated, furnishing a broad concave articulating surfacefor the accommodation of the tuberculum of the corresponding rib.On either side of the centrum of the first six dorsals, just anteriorto the posterior epiphysis, is a circular digital depression for theaccommodation of the capitulum of the following rib. On theeighth dorsal (pi. 13, fig. 4) the articular facet for the capitulum liesjust below that for the tuberculum. A corresponding facet is notpresent on the last two dorsals for the ribs articulate solely with thetransverse processes.The facets for the tubercles of the ribs increase in width from thefirst to seventh dorsals, and gradually shift in position until on theseventh dorsal the facet is behind the level of the anterior epiphysisof centrum. On the anterior dorsals the facet for the tubercleprojects in front of the anterior epiphysis. The lateral transverseprocess which bears the articular facet for tubercle of rib and whichinternally is continuous with metapophysis increases in size fromthe first to seventh dorsal. The transverse process drops down tothe level of the centrum on the eighth dorsal. The neural canalis roughly semicircular in outline inferiorly, but above, owing tothe depression of the neurapophyses, it is pointed, as shown inplate 13, figure 2. The anterior articulating surfaces of the centraare convex, while the posterior faces are slightly concave.
AET. 14- MARYLAND FOSSIL PORPOISE KELLOGG. 31
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32 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 63,LUMBAK A'ERTEBRAB.Four lumbar vertebrae (pi. 10, Nos. 12-15) are preserved, but twoare incomplete; the second lacks the posterior end of the centrumand its epiphysis, and of the third only the neural spine remains.The centra of two of these lumbar vertebrae, one of which is prac-tically complete with the exception of some defects due to crushing,were utilized in restoring the second vertebra of the series. Theyare all considerably longer than broad, and, although the fourthlumbar is the longest, no conspicuous increase in the length of thecentra between the first and fourth is apparent. The centra areroughly cylindrical in outline. Inferiorly the centra of the first andsecond lumbars show a tendency to develop a median keel. This isevidenced by depressed areas on each side of the centrum below thetransverse processes. The fourth centrum has a well developed keelwhich is more pronounced at the middle than at either end. A pairof grooves meeting mesially at the keel and directed obliquely outwardand backward pass below the posterior margin of the transversej)rocess and characterize the fourth lumbar.The neural spines of the vertebrae of this fossil porpoise, if theywere arranged in regular serial order and position would describea gentle curve arising from the first dorsal and declining from thefourth lumbar. These neural spines, viewed laterally, are stronglyflattened, rather squarely truncated on their upper extremities, andvertical in position. The neural arch is preserved on three of thefour lumbars. The arch is very broad antero-posteriorly, withconcave anterior and posterior margins. The posterior margin ofthe neural spine is slightly concave. The spine is broader antero-posteriorly than the neural arch, and slightly expanded at the tip.Tlie metapophyses are situated a little nearer to the free edge of thespine than to the centrum and are directed obliquely upward andforward.There is no distinct process for the prezygapophysis. The prezyga-pophysial facets (pi. 15, fig. 6), which are formed on the superiorface of the upturned margin of the laminae in front of and belowthe point where the metapophyses arise, are concave, and lookupward, inward, and forward. The postzygapophyses are laterallyconvex, and look downward, outward, and backward, but do notoverhang the posterior face of the centrum. The transverse proc-esses (pi. 10, Nos. 12-13) are broad, flattened, and project horizon-tally outward. They are also moderately long, very thin, andexpanded (pi. 10, No. 15) at the distal end. This type of lumbarcharacterizes the genus Platanista.
ART. 14. MARYLAND FOSSIL POEPOTSE?KELLOGG.Measurements of lumbar vertebrae {in millimeters). 33
Greatest depth (vertically) of vertebra (tip of neuralspine to inferior face of centrum)Height of anterior face of centrumBreadth of anterior face of centrumHeight of posterior face of centrumBreadth of posterior face of centrumGreatest length of centrumDistance across vertebra between tips of the transverseprocesses (as preserved)Distance between the tip of left post-zygapophysis andtip of left pre-zygapophysis (as preserved)Minimum length of neurapophysisAntero-posterior breadth of neural spine in a horizontalline immediately above the zygapophysesAntero-posterior diameter of left transverse process at ex-tremityVertical height of neural spine (distance between supe-rior margin of spinal canal and tip of spine)
19657X62X103277XX76X
21161XXX111
558058108+1 119
242.069.078.072.082.0123.526L0144.063.099.090.0148.0
CAUDAL VERTEBRAE.Onl}^ three caudal vertebrae have been preserved and they belongnear the distal end of the series. In form they somewhat resemblethe caudals of Inia geojfrensis though the vertebral canals are rela-tively larger than in Inia. The largest of these caudals (pi. 18, fig.5) is almost circular in outline, while the remaining two (pi. 18,figs. 6-7) are smaller and somewhat flattened dorso-ventrally. The
"iides of both of the last-mentioned caudals are grooved.All of these caudals are pierced dorso-ventrally by two large ver-tebral canals. On the ventral face of the largest caudal (pi. 17,fig. 1) there are two openings for each vertebral canal of which theexternal ones are nearly closed. The double keels on the ventralface of the largest caudal are approximately parallel and inclosea narrow concave area. The vertebral canals converge ventrally andin the small terminal caudals (pi. 17, figs. 2-3) open only into thelongitudinal depressed area. The ventral openings of these canalsare partiallj' concealed by overhanging bony shelves. The dorsalopenings of the vertebral canals (pi. 17, figs. 4r-6) are large andwide apart.The presence of a pair of neurapophyses on the largest caudalshows that all of the caudal vertebrae with the exception of the ter-minal ones possess a neural arch. The neurapophyses of the largestcaudal (pi. 17, fig. 4) converge mesally and partially close the neuralcanal posteriorly. The anterior articulating surfaces of the caudals(pi. 18, figs. 5-7) are concave, while the posterior are convex.
34 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 03.Measurevients of caudal vertebrae (in millimeters.)
Height of centrum anteriorly 63.Breadth of centrum anteriorly 58. 5Height of centrum posteriorly 53. 5Breadth of centrum posteriori}- 54.Greatest thickness of centrum 52.
PI. 18, PI. 18,Fig. 6. Fig. 7.
58.054.0 47.061.045.5 47.550. 58.43.5 39.0
Chevron hones.Four chevron bones were found in the matrix surrounding theskeleton. One of them (pi. 18, "fig. 1) is small, elongated, and rela-tively low. Another (pi. 18, fig. 2) which belongs farther back issomewhat deeper and broader. The chevrons have elongated flat-tened surfaces for articulation with the corresponding facets on thecaudals. The free margin forms a narrow posterior projection anda blunt anterior projection. EIBS.The whole, or portions, of 16 ribs are preserved. Only one of theribs was found associated with the corresponding vertebra ; the otherslay in a tangled pile alongside of the anterior lumbars. Eight ofthem (pi. 10) were left imdisturbed when the slab in which theywere imbedded was prepared for exhibition; the others were freedfrom the matrix.This fossil porpoise possesses 10 ribs on each side, of which thefirst is the shortest. The ribs rapidly increase in length from thefirst to the sixth (pi. 16, fig. 5), which is the longest, and then de-crease in length to the tenth (pi, 16, fig. 7). The couA^ex externalcurvature of the shafts of the three anterior ribs is less pronouncedthan in the others ; this curvature rapidly increases posteriorly, reach-ing its maximum development in the fifth, sixth, and seventli ribs.The curvature of these last-mentioned ribs is very nearly the same.All of the ribs show at their distal end provision for the attachmentof cartilages. The capitula of the first to the seventh ribs are borneupon long necks and the length of the necks increase as we go back-ward along the series to the seventh. On the eighth, ninth, andtenth ribs the capitulum and tuberculum are fused with each other.The first seven pairs of ribs have capitula articulating with thecentra, as well as tubercula articulating with the transverse pro-cesses ; in the three posterior ribs, however, the articulation is limitedto the transverse process. Four pairs of ribs are connected by carti-lage with the sternum in Platanista and similar relations may havebeen maintained in this fossil porpoise.The first three ribs are greatly compressed and their proximal por-tions are bent at right angles to the shafts. The first rib (pi. 16, fig. 1)is short, flattened, and thickest at its distal extremit}^ ; the capitulum
ART. 14. MARYLAND FOSSIL PORPOISE?KELLOGG. 35
is borne upon a relatively long flattened neck which is strongly con-stricted behind the capitulum. The tuberciilum and capituliim arerelatively small. The second rib (pi. 16, fig. 2) is longer than thefirst, with narrower shaft and neck. The capitulum is larger than thetuberculum. The third rib is characterized by a longer shaft and theneck, while flattened, is even thicker than the second.The angle formed by the neck with the shaft of the succeeding ribsbecomes less and less acute until in the posterior ones it almost dis-appears and the ribs are regularly curved. The ninth and tenth ribs(pi. 15, fig. 4?5) retain only vestiges of the angle in the form of aslight swelling below the fused tuberculum and capitulum.The fourth, fifth, sixth, and seventh ribs are all very much alike.The differences consist of a constant narrowing of the shaft at theangle as we go backward from the fourth (pi. 16, fig. 3) to the seventhribs, and in addition there is a tendency toward the lengthening of theinterval between the capitulum and the tuberculum. The seventhrib (pi. 15, fig. 2) is larger and heavier than any of the others.In this fossil porpoise the long necks and the distinct capitula donot disappear until the eighth rib (pi. 15, fig. 3) and up to this pointare well developed. Upon the eighth rib the tuberculum and capi-tulum disappear as separate facets. The posterior face of this singlefacet on the eighth and ninth ribs is indented by a well-marked con-cavity. The position of this concavity suggests that the neck hasbeen shortened and in consequence the capitulum and the tuberculumhave coalesced. If this determination is cprrect, then the capitulumhas not been lost as some writers have held. The eighth and ninthribs are very much alike except that the former is more convex. Theshaft of the tenth rib does not curve as much as the anterior ribs.Measurements of ribs (in millimeters).
Total lenqrth in a straight lineGreatest breadth at ane;le. .
.
Greatest breadth at inferiorextremityDistance between externalmar^n of tubercle andheadGreatest thickness of rib nearthe middleGreatest thickness at the in-ferior extremity
^
36 PROCEEDINGS OF THE NATIONAL MUSEUM. vui,. c,:!.
Although the presternum (pi. 11, fig. 1) of this fossil porpoise iscrushed and incomplete, it is evident that it must have resembledPlatanista when perfect. In size it approaches the presternum ofInia, but there are no traces of conical processes behind the articularsurfaces for the first ribs. The anterior extremity is imperfectlypreserved and both angles are missing. The presternum is largerthan that of Platanista and smaller than that of Inia; the posteriorextremity is abruptly truncated. The breadth of the presternumposteriorly (52 mm.) equals about one-half of the mesial length(113 mm.). The external margins are rounded and the bone, as awhole, is relatively thick (greatest thickness 24.5 mm.). The ar-ticular surfaces for the second ribs are situated on the external faceand at the posterior end of the presternum, and not on the posteriorface as in Platanista.A pair of curved plate-like bones (pi, 11, fig. 2) which are unitedon their antero-internal margins may represent the mesostemum.Such a type of mesosternum would be somewhat unusual. The meso-stemum of Platanista is composed of two flattened bones which arein contact for their entire length.PADDLE BONES.Although the phalanges (pi. 9, fig. 4) have been arranged inaccordance with the position of similar phalanges in the paddle ofInia geo-ffrensi-s., no assurance can be given that this arrangement iscorrect. These bones were found intermingled with other parts ofthe skeleton and may represent parts of both paddles.EXPLANATION OF PLATES.Zarhacliis flagellator Cope. Cat. No. 10485, Division of Vertebrate Palaeon-tology, United States National Museum. Calvert formation, western shore ofChesapeake Bay, about one-half mile south of Chesapeake Beach, CalvertCounty, Maryland. Collected by Norman Boss, August 8, 1921.Plate 1.Skull of Zarhachis flagellator Cope. About % natural size. Upper figure.Dorsal view ; Lower figure. Ventral view. The posterior end of the skull hasbeen i-estored. Abbreviations: Ex. pt., external pterygoid; Fo. inf., infraorbitalforamen ; Fr. frontal ; In pt., internal pterygoid ; Max., maxilla ; Max. cr., max-illary crest ; A^ A., external nasal apei-ture ; Na., nasal ; Pmx., premaxilla ; Po.gl. p., postglenoid process of squamosal ; Po, p., postorbital projection of frontal
;
Pr. p., preorbital projection of frontal ; Prs., presphenoid ; So., supraoccipitalS. or. pr., supraorbital process of frontal ; V., vomer ; Ziig., zygomatic process ofsquamosal.
AKT. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 37Plate 2.Skull of Zarhachis flagellator Cope. Lateral views. Upper figure, Distalend of rostrum ; Middle figure, Section of skull. Lower figure, Entire skull,about Vo natural size. Abbreviations: Er pt., external pterygoid; Fo. inf.,infraorbital foramen; Max., maxilla; Pm.c, premaxilla ; Po. gl. p., postglenoidprocess of squamosal ; Po. p., postorbital projection of frontal ; 8. or. pr., supra-orbital process of frontal; V., vomer; Zyg., zygomatic process of squamosal.Plate 3.Mandibles of Zarhachis flagellator Cope. Upper figure, Ventral view of man-dibles ; Lower figure, Dorsal view of mandibles. About Vs natural size. Abbre-viations : Ang., angle ; C. condyle ; Cor. coronoid process.Plate 4.Skull of Zarhachis flagellator Cope. About % natural size. Lateral view,showing external pterygoid and surrounding bones. Abbreviations : Ch., chan-nel or shelf formed between external pterygoid and frontal ; Ex. pt., externalpterygoid ; Fo. inf., infraorbital foramen ; In. pt., internal pterygoid ; Max.,maxilla ; Max. dep., maxillary depression ; Po. gl. p., postglenoid process ofsquamosal ; S. or. pr., supraorbital process of frontal ; V., vomer ; Zyg., zygo-matic process of squamosal. Plate 5.Skull of Platanista gangetica Lebeck. About % natural size. Lateral view.The external and internal pterygoids have been removed to show position ofthe palatine. The right squamosal and its zygomatic process has also beenremoved. Abbreviations : Bo., basioccipital ; Bs., basisphenoid ; C, condyle
;
Ex. 0., exoccipital ; Fo. inf., infraorbital foramen ; Fr., frontal ; In. pt., internalpterygoid; Max., maxilla; Max. cr., maxillary crest; PI., Palatine; S. or. pr.,supraorbital process of frontal ; V., vomer.Plate G.Skull of Platanista gangetica Lebeck. About % natural size. Lateral view,showing external pterygoids and surrounding bones. The right maxillarycrest has been removed. Abbreviations : Bo., basioccipital ; Bs., basisphenoidC, condyle, Ex. o. exoccipital ; Ex. pt., external pterygoid ; Fo. inf., infra-orbital foramen ; Fo. ov., foramen ovale : Fr., frontal ; In. pt., internal ptery-goid ; Lac, socket for insertion of lachrymal; Max., maxilla; Max. or., maxil-lary crest ; Po. gl. p., postglenoid process of squamosal ; S. or. pr., supraorbitalprocess of frontal ; Sq., squamosal ; V., vomer ; Zijg.. zygomatic process ofsquamosal. Plate 7.Fig. 1, Left tympanic of Platanista gangetica Lebeck, Superior view ; 2, Leftt.vmpanic of Zarhachis flagellator Cope, Superior view; 3, Right tympanic ofPlatanista gangetica Lebeck, Internal view; 4, Kight tympanic of Zarhachisflagellator Cope, Internal view ; 5, Left periotic of Platanista gangetica Lebeck,Inferior view ; 6, Left periotic of Zarhachis flagellator Cope, Inferior view,posterior process missing; 7, Left periotic of Plantanista gangetica Lebeck,Internal view; 8, Left periotic of Zarhachis flagellator Cope, Internal view,posterior process missing. All figures about % natural size.
38 PROCEEDINGS OF THE NATIONAL MUSEUM. vor.. 63,Platk S.Fig. 1. Right tympanic of Platanista gangetica Lebeek, External view ; 2,Rigtit tympanic of Zarhachis flagellator Cope, External view ; 3, Left tympanicof Platanista gangetica Lebeek, Inferior view; 4, Left tympanic of Zarhachisflagellator Cope, Inferior view ; 5, Atlas of Zarhachis flagellator Cope, Dorsalview. Figs. 1^, about tu natural size ; Fig. 5, about Mj natural size.Plate 9.Fig. 1, Basihyal, ceratohyals, and tbyrohyals of Zarhachis flagellator CopeDorsal view ; 2, Right stylohyal of Zarhachis flagellator Cope, Dorsal view ; 3,Left stylohyal of Zarhachis flagellator Cope, Dorsal view. All figures about% natural size. 4, Paddle bones of Zarhachis flagellator Cope. The bones havebeen arranged in a graded series, but do not represent necessarily their truepositions. About tt natural size. Plate 10.Vertebral column and ribs of Zarhachis flagellator Cope. Viewed as foundin the matrix. 1, Atlas ; 2, First dorsal ; 3, Second dorsal ; 4, Third dorsal ; 5,Fourth dorsal; 6, Fifth dorsal; 7, Sixth dorsal; 8, Seventh dorsal; 9, Eighthdorsal ; 10, Nintli dorsal ; 11, Tenth dorsal ; 12, First lumbar ; 13, Secondlumbar ; 14, Third lumbar, centrum missing ; 15, Fourth lumbar ; 16, Posteriorcaudal ; 17, Posterior caudal ; 18, Posterior caudal ; 19, First rib, right side
;
20, Fourth rib, right side; 21, Third rib, left side; 22, Fourth rib, left side;23, Fifth rib, left side; 24, Eighth rib, left side; 25, Ninth rib, left side; 26,seventh rib, right side. All elements about Ys natural size.Plate 11.Fig. 1, Presternum of Zarhachis flagellator Cope, Superior view ; 2, Mesoster-num of Zarhachis flagellator Cope, Superior view. Both figures about M: natu-ral size. Plate 12.Fig. 3, Posterior view of atlas of Zarhachis flagellator Cope; 4, Anterior view.Both figures about % natural size.Plate 13.Dorsal vertebrae of Zarhachis flagellator Cope. About % natural size. Fig.1, Eighth dorsal vertebra, Anterior view ; 2, Fourth dorsal vertebra, Anteriorview, showing missing epiphysis. 3, Fourth dorsal vertebra, Lateral view; 4,Eighth dorsal vertebra, Lateral view.Plate 14.Dorsal vertebra of Zarhachis flagellator Cope. About Y^ natural size. Fig.1, Fourth dorsal vertebra, Posterior view; 2, Eighth dorsal vertebra. Posteriorview. Plate 15.Ribs of Zarhachis flagellator Cope, Left side. About % natural size. Fig.1, Sixth rib ; 2, Seventh rib ; 3, Eighth rib ; 4, Ninth rib ; 5, Tenth rib ; 6, Fourthlumbar vertebra (about % natural size).
ART. 14. MARYLAND FOSSIL PORPOISE?KELLOGG. 39Plate 16.Ribs of Zarhachis fiagellator Cope, Right side. About Vs natural size. Fig.1, First rib ; 2, Second rib ; 3, Fourth rib ; 4, Fifth rib ; 5, Sixth rib ; 6, Ninthrib ; 7, Tenth rib. Plate 17.Posterior caudal vertebrae of Zarhachis flagellator Cope. About % naturalsize. Figs. 1-3, Inferior views of caudals; 4-6, Superior vievs^s of caudals.Plate 18.Figs. 1-4, Chevrons of Zarhachis flagellator Cope, Lateral view ; 5-7, Caudalvertebrae of Zarhachis flagellator Cope, Anterior view.s. All figures about %natural size.

U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. I
Dorsal and Ventral Views of Skull of Zarhachis flagellator.For explanation of plate see page 36.
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 2
Lateral View of Skull of Zarhachis flagellator.For explanation of plate see page 37.
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL 3
Dorsal and Ventral Views of Mandibles of Zarhachis flagellator.FOR EXPLANATION OF PLATE SEE PAGE 37.
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 4
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U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 5
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. K PL. 6
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U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 7
Views of Tympanic and Periotic Bones.For EXPLAN4TI0N OF PLATE GEE PAGE 37.
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 8
Views of Tympanic Bones (|-4) and Dorsal View of Atlas (5).For explanation of plate see page 38
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 9
Hyoid Bones of Zarhachis flagellator.For explanation of plate see page 38
Bones in the Manus of Zarhachis flagellator.For explanation of plate see page 38
U.S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 10
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U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. U PL. II
Sternum of Zarhachis flagellator.For explanation of plate see page 38.
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. K PI.. 12
Views of Atlas of Zarhachis flagellator.For explanation of plate see page 38
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 13
Views of Dorsal Vertebrae of Zarhachis flagellator.For explanation of plate see page 38.
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 14
Posterior Views of Dorsal Vertebrae of Zarhachis flagellator.For EXPLArMTION OF PLATE SEE PAGE 38
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 15
Views of Ribs of Zarhachis flagellator.
Anterior View of Fourth Lumbar Vertebra of Zarhachis flagellator.For explanation of plate see page 38
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63. ART. 14 PL. 16
Views of Ribs of Zarhachis flagellator.For explanation of plate see page 39.
U. S. NATIONAL MUSEUM PROCEEDINGS. VOL. 63, ART. U FL. H
Views of Posterior Caudal Vertebrae of Zarhachis flagellator.For explanation of plate see page 39
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 63, ART. 14 PL. 18
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Chevron Bones and Posterior Caudal Vertebrae,FOR EXPLANATION OF PLATE SEE PAGE 39.