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Show 122 necting ridge is low, and there is only a trace of a descending posterior cingnlnm en the posterior crest. Measurements. M-Width of last superior molar .. .040 Length of last superior molar .030 Length of last inferior molar .-.- i089 Width of last inferior molar - - 096 Elevatiou of posterior crest of inferior molar 015 Elevation of anterior crest of inferior molar 025 A remarkably fine skeleton of a species of this genns, discovered by my friend and assistant, William 6. Shedd, exhibits characters heretofore only inferential, and demonstrates the correctness of a number of positions heretofore based on a few fragmentary bones. The feet exhibit proboscidian characters throughout. They are very short and plantigrade, and there are five digits on the hind foot. The oalcaueum is recurved inward, and th « astragalus flat above. The navicular is transverse and very thin, while the cnboid is subequilateral. The metatarsals are short, and the phalanges mnch wider than long. The cranium remarkably resembles that of a carnivorous animal in its massive expanded zygomas and huge canine tusks. It differs remarkably from this type, and shows its affinity to Vintatherium in the broad plane of the upper cranial wall, with overhanging marginal crests for the attachment and protection of the temporal and neck muscles. These crests do not support horns. The muzzle is contracted at the diastema, thns rendering more prominent the ridges which mark the position of the alveoli of the tusks. The latter are directed downward, giving the profile the pick- ax- like form of that of Uinlatherium, though more robust in its proportions than the latter. The length of this skull is 19 inches; the width at the zygonias 13. PHENACODUS PRIMWEVUS, Cope.* Char. gen.- The genus Phenacodus was first recognized by the writer in a posterior inferior molar of a mammal of about the size of a hog, of unknown affinities, which was named P. pnmatvus. Specimens of the same species, embracing the dentition of both jaws, having been procured in the Eocene of New Mexico, I am prepared to add to the characters of the genus. There are three molars in each jaw, and the specimens iuclude two premolars, which form a continuous series, as in Achanodon. There are four principal tubercles on the inferior molars and sometimes a third small one between the posterior pair, always on the last one, which is, however, not largely developed. The first inferior premolar presents a broad heel, a double medium tubercle, and an anterior tubercle, ( in P. pri-m( Ecu$.) The crowns of the superior molars are low and broad, and support numerous tubercles; these are low and vary in number, but there are two near the external border which are quite constant. They have general resemblances to those of hogs, bears, and monkeys. The first tme molar is broader than long, and there are no di as tern at a between it and the premolars, or between the latter, which are quadri-, and tri- cuspid, respectively. The forms of these teeth are entirely different from those of the. corresponding teeth in Elotkerium. Char, specif.- The posterior molar of the left side is wide in front and regularly oval in posterior outline, and has two equal anterior aud three unequal posterior tubercles. One of the posteriors is situated near the middle of the outer side, and is separated from the adjacent anterior by a deep groove. The corresponding inner tubercle is more posterior; anterior tubercles low, trihedral, and counectedby a shelf- like cingnlum across the front of the tooth: rudimental cingula on outer side of crown. The penultimate molar has three tubercles on the posterior border; aud a deep tissue, corresponding to that of the last molar, separates one of them from the anterior tubercle. Measurements, M. Length of last molar 015 Width $ a n t e r i o r l y - 011 j between two posterior tnbercles 005 Elevation of anterior cusp from base 008 Width of penultimate molar behind .010 From the same locality as the preceding species. PHENACODUS OMNIVORUS, sp. nov. Superior molar with low and broad tubercular crown, with outline of base parallelo-grammic, with one cud oblique; the oblique end with two principal low tnbercles, * Paleontologies! Bulletin, No. 17, p. 3, October 25,1873. |
