1882.] 4b 4 [Cope. 



ridge on the external side of the posterior face of the principal lobe of the 

 tooth. 



The sides of the premolars present rather distinct ridges, as in Peripty- 

 chus carinidens. The second true molar has two anterior and three poste- 

 rior tubercles ; the latter close together, pointed and of about equal size. 

 Of the anterior tubercles, the external is much the larger and more ele- 

 vated. It is compressed and has a curved subacute anterior edge, Avhich 

 extends much in front of the internal tubercle. There is no anterior inner 

 tubercle, nor are there any cingula. The enamel of the sides of the crown 

 presents a few vertical ridges. The last inferior molar only differs from 

 the second, in the greater size of the median posterior lobe, which is never- 

 theless smaller than in the two other species of Haploconus. 



There is a mental foramen below the posterior edge of the second in- 

 ferior premolar. 



Measurements. M. 



Length of last five inferior molars 0250 



" third premolar 0050 



" fourth premolar 0066 



" second true molar 0050 



Width of second true molar 0032 



Length of third true molar 0050 



Depth of ramus at P-m. iii 0095 



M. iii 0130 



The two rami with the temporary premolars, exhibit the last true molar 

 enclosed in the jaw. The third and fourth premolars are much like the fourth 

 premolar of the specimen above described, but the fourth is a little more 

 robust than that of the latter, which is very much like the third of the de- 

 ciduous series. The space occupied by the supposed first premolar of the 

 type specimen is too short for the fourth premolar of the deciduous series, 

 otherwise it might be supposed to have occupied that position. The two 

 true molars resemble those of the type, excepting that the last one does 

 not extend so far into the base of the coronoid process, and is in accord- 

 ance with the position as number two in the series. 



The specimens were procured by Mr. D. Baldwin in the Puerco beds of 

 New Mexico. 



Haploconus entoconus Cope, loc. cit. 1882, p. 686. 



Anisonchus coniferus Cope, loc. cit. 1882, October (September), p. 832. 



Anisonchus gillianus Cope. Haploconus gillianus Cope, loc. cit., 1882, 

 p. 686. 



Anisonchus sectorius Cope, Proc. Amer. Philos. Soc. 1881, p. 488, Mio- 

 claenus sectorius, Amer. Nat. 1881, p. 831. 



Hemithlceus kowalevskianus Cope, Amer. Nat. 1882, p. 832. 



Hemithlceus opisthacus Cope. Mioclcenus opisthacus, 1 c. 1882, p. 833. 



Gonoryctes comma Cope American Naturalist, 1881, p. 829. 



PROC. AMER. PHILOS. SOC. XX. 112. 3<j. PRINTED NOVEMBER , 1882. 



