G54 THE WASATCH AND BRIDGER FAUN^. 



Heptodon posticl's Cope. 



Pachynolophua posticus Cope, Paleontological Bulletin, No. 34, i). 187, Dec, 1881 (published Feb. 20, 1882). 



Plate LVI; fig. 6. 



Both ranii of a mandible represent this large species. They are some- 

 what 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 

 valleys 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 sjDecies of Bhiuocerus. 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, 



H. 



Length of crowns of posterior six molars 0700 



Length of crowns of true molars 0440 



^ anteroposterior 0095 



Diameters Pm. '^y \ ^^^^^^^^,^ 0070 



Diameters M.ii^''"**^°P°^'«"''^ - '^^^'^ 



( transverse 0095 



Diameters M.iii 5 ''"^'"■•'P"^*''""'' "^l^" 



( transverse anteriorly 0092 



Depth of ramus at Pm. ii 0280 



Depth of ramus at M. ii 0310 



From the Big Horn basin and Wasatch epoch; J. L. Wortman. 

 Heptodon ventorum Cope. 



Paehynolophus ventorum Cope, Bulletin U. S. Geol. Surv. Terrs., 1881, VI, p. 197. Lophiodon ventorum 



Cope, American Naturalist, 1880, p. 747. 



Plate XXIX a; figs. 4, 5. 



Portions of the crania of six individuals represent this species. These 

 are mostl}- fragmentary mandibles and maxillary bones. The most charac- 

 teristic specimen includes the left maxillary bone almost entire, a part of 

 the right maxillary, and the posterior part of the left ramus of the mandi- 

 ble, with the third true molar in place. 



