1879.] "'^ [Cope. 



HOPLOPHONEUS PLATYCOPIS Cope. 



American Naturalist, 1879, p. 7986, December. 



This is the largest sabre tooth discovered in North America. It was twice 

 the bulk of the II. primcevus Leidy, and differs from that species and the 

 //. occidentals in the relatively larger size of the premolar teeth, which are 

 less obliquely placed than in the latter. The first superior premolar is very 

 small. The canine is large and compressed as in the species of Machmrodus, 

 and has serrulate posterior and anterior cutting edges. Inferior incisors 

 with conic crowns. The symphysis is very deep in consequence of the 

 large development of the inferior flares for the canines. Sagittal crest 

 making a steep angle with the front. 



Total length of cranium, M., .280 ; zygomatic width, .192 ; length from 

 orbit to superior incisors, .095 ; length of inferior sectorial, .025; of in- 

 ferior sectorial, .022 ; length of inferior molar series, .055 ; length of crown 

 of superior canine, .060 ; width of superior canine at base, .026. This skull 

 is less than one-sixth smaller than that of the Bengal tiger ( JJncia tigris). 

 Ch^nohyus decedens, gen. et sp. nov. 



The characters of this genus will be best understood by comparison with 

 those of the two other genera of suilline animals which occur in the same 

 formations. 



Premolars three, a wide diastema between the anterior one 



and its successor Ghceiiohytis. 



Premolars four ; diastemata before and behind the first . . . Thinohyus. 

 Premolars four, in a continuous series Palmocliozrus. 



It is then apparent that Ghmnohyus differs from Dicotyles in having the 

 diastema behind the anterior premolar instead of in front of it. 



Char. spec. This hog is represented in the collection of Prof. Condon 

 at Eugene City, Oregon, by the anterior part of a cranium, which includes 

 both maxillary bones. Its size is a little less than that of the Dicotyles 

 torquaius. The series of maxillary teeth is slightly convex externally, 

 and the teeth diminish rapidly in size anteriorly. The difference in dimen- 

 sions between the first and last true molars is much greater than in the 

 other suillines of this period known to me. The external tubercles of the 

 true molars are somewhat flattened externally, and a distinct cingulum 

 passes entirely round their external bases. The first superior premolar has 

 one root, the other premolars possess two. 



I suspect that the Dicotyles liesperius of Marsh belongs to ChcenoJiyus. 

 It differs from the C. decedens in its materially smaller size. According to 

 Marsh, it is considerably smaller than his Thinoliyus socialis, which is 

 about as large as the C. decedens. 



Discovered by Prof. Condon in the region of the John Day river. 



TlIINOH-kUS TRICHrEXUS, Sp. nOV. 



Represented by the greater part of the maxillary and mandibular bones 

 of both sides, with teeth. 



PKOC. AMEK. PIIILOS. SOC. XVIII. 104. 2v. PRINTED DEC. 30, 1879. 



