354 SYNOPSIS OF THE VERTEBRATE FAUNA OP THE PUERCO SERIES. 



PERIPTYCHUS Cope. 

 Amer. Naluralist, 1881, p. 337 ; Tertiary Vertcbrata, 1885, p. 387. 



Peuu'tychus coaectatu.s Cope ; Tertiary Vertebrata, PI. XXIX d, explanation, and flgs. 7-8 ; Amer. Naturalist. 

 1884, p. 801, fig. 10. 



This with the P. brabensis, is characteristic of the lower beds of the Puerco, as 

 the P. rliaModon is of the upper beds. It is not so abundant as cither of the others, 

 only five individuals having come into my possession. 



This species is of smaller size than the P. rhahdodon and the P. carinidens, 

 and is especially distinguished from both, in that the cingulum of the inferior 

 premolars is not continuous on the inner side of the crown, but is confined 

 to the anterior and posterior bases, sometimes to the posterior base exclu- 

 sively. The first and second premolars are larger than the true molars, and the latter 

 diminish in size posteriorly. In the inferior molars the fifth cusp is present, and as 

 in the premolars there are traces of external cingula. The grooved sti'iation of the 

 crowns is distinct. The characters which distinguish the species from the P. braben- 

 sis are the following. The transverse diameter of the superior premolars is relatively 

 much greater than in the P. rhabdodon and P. brabensis, and the true molars have a 

 transversely compressed form. There is a faint cingulum on the external base of the 

 true molars and first premolar in both jaws, at which the grooves of the enamel tei*- 

 minate abruptly. This is wanting in the P. brabensis. The external faces of the supe- 

 rior premolars are directed obliquely forwards and inwards, a character not seen in 

 the P. brabensis. 



Measurements of Superior Molars. M. 

 anteroposterior Oil 



Diameters i). ui. i , „,. 



transverse 016 



f anteroposterior Oil 



Diameters p. ni. ii \ ,„„ 



(^ transverse 016 



f anteroposterior 0095 



Diameters m. ii ^ „. , 



( transverse 013 



PEIUrTYCnUB BRABENSIS Sp. nOV. 



Twenty individuals represent this species in my collections, nearly all of them 

 consisting of jaws only. Of these four only present the dentition of both jaws ; one 

 exhibits nearly the entire dentition of both maxillary bones, and one the last tempo- 

 rary molar of the lower jaw. 



This species is still smaller than the P. coarctatus, and diifers from it in the 

 same way, i. e., in the non-continuation of the cingulum across the interior 

 side of the inferior premolars. But it diflers from the P. coarctatus, as already 



