194 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [Yol.YL 



AMBLYPODA. 



PANTODONTA. 



31. COEYPHODON CUSPIDATUS Cope. 



Part of tlie dentition of one individual. 



32. CORYPHODON KAOLINS Cope. 



Apparently an abundant species. 



DINOCERATA. 



33. Bathyopsis fissidens gen. et sp. nov. 



Char. gen. — These can only be given as seen in the mandible, the 

 only part of the skeleton in my possession. Dentition : I. 3 j C. 1 ; Pm. 

 4 ; M. 3. Incisors, canine, and first premolar forming an uninterrupted 

 series, which is separated by a diastema from the molar series. The 

 molar and premolar teeth are constructed on an identical pattern, pre- 

 senting slight modifications from front to rear. This consists of an an- 

 terior elevated transverse crest, and a posterior heel with raised poste- 

 rior border ; between these is situated on the external side an elevated 

 cusp, which sends a low ridge inwards and forwards. The inner ex- 

 tremity of the anterior crest is cusp-like, and is accompanied by a second 

 internal anterior cusp immediately posterior to it. The mandibular 

 ramus has great vertical depth, its inferior border being convex down- 

 wards throughout its entire length. Symphysis coossified. 



The above characters indicate a new genus of considerable interest. 

 Its form differs from that of the two genera where it is known, viz, 

 Uintatherium and Loxolophodon, in the much greater development of the 

 inferior expansion. In Loxolophodon it has been shown by Messrs. 

 Speir and Osborne to be represented by a mere convexity. In Uinta- 

 therium Marsh has discovered it to be confined to the anterior part of the 

 jaw, as in the sabre-tooth cats. In Bathyopsis it extends to the entire 

 length of the ramus, giving an outline in profile much like that of Mega- 

 therium. The anterior extremity of the symphysis projects beyond the 

 line of the anterior border of the inferior expansion. 



The characters of the inferior molars in this and other genera of Dino- 

 cerata are very pecuhar. In Bathyopsis they are constructed on the plan 

 of those of insectivorous marsupial and placental mammals, so as to lead 

 to the suspicion that its food consisted of Crustacea, or insects of large 

 size, or possibly of thin-shelled mollusca. 



Char, specif. — This species was probably about the size of the Malayan 

 tapir. The symphysis mandibuli is quite narrow, and its superior exca- 

 vation is deep. It extends as far posteriorly as the middle of the dias- 

 tema. It has considerable vertical thickness. The anterior edges of 

 the lateral exi^ansions are truncate, and present an obtuse angle out- 

 wards, which forms the anterior boundaries of the slight concavity of the 

 lateral face. The middle of the expansion below the first premolar tooth 

 is slightly convex. This wall encloses a large internal expansion of the 



