187 



[Cope. 



first molar .0067 ; depth of ramus at M. I, .0120. The dimensions of the 

 larger variety are : length of M. iii, .110 ; of M. i, .0067 ; depth ramus 

 .0165. The New Mexican forms originally described, exhibit combinations 

 of several of these measurements. 



Pachynolophus ventorum Cope. 



Bulletin U. S. Geol. Surv. Terrs., 1881, p. 197. American Naturalist, 

 1880, p. 747. 



One mandibular ramus. 



Pachynolophus posticus, sp. iiov. 



Both rami of a mandible represent this large species. They are somewhat 

 injured, and the crowns of five of the molars only can be distinctly seen. 

 The latter display the characters seen in the P. ventorum and other species 

 of the genus. The transverse crests are well characterized, and the valley 

 between them uninterrupted. They are closed at the inner extremity by 

 a low ridge nearly at right-angles with the cross crest posterior to them, 

 as in the species of Rhinocerus. The anterior of these bounds an anterior 

 ledge, which is quite large on the last true molar. The latter has a rather 

 narrow, but prominent heel, which rises posteriorly. The fourth premolar 

 has an anterior ledge, and wide heel with a diagonal crest which is median 

 in front. The third premolar is similar, but smaller. The only cingulum 

 is seen on the anterior part of the external side of all the true molars. 



Measurements. M. 



Length of crowns of posterior six molars 0700 



" " true molars 0440 



^. ^ . (-anteroposterior 0095 



Diameters P-m. iv -( , r,nr,n 



\ transverse 0070 



,^ .. f anteroposterior 0130 



Diameters M. ii < ^ f^nrlc 



\ transverse 0095 



^. „ ... f anteroposterior 0180 



Diameters M. m ■( , ^ • i nnnn 



( transverse anteriorly 0092 



Depth ramus at P-m. ii 0280 



M. ii 0310 



ARTIODACTYLA. 



MlOCL^NUS BRACHYSTOMUS, Sp. nOV. 



Char. gen. The typical specimen of this species is represented by all 

 the'molar dentition of both jaws excepting the anterior three superior pre-^ 

 molars. It also includes pelvis, femur, the distal parts of the tibia and 

 fibula, the entire tarsus and the proximal portion of the metatarsus. 



The dental characters conform precisely to those of the other species of 

 Miodmnus. There is but one internal cusp of the superior true molars, 

 and the intermediate tubercles are present. The fourth premolar has one 

 external and one internal lobe. The inferior premolars have simple crowns 

 without interior cusps or tubercles. 



PROC. AMER. PHILOS, SOC. XS. 111. X. PRINTED APRIL 4, 1882, 



