HEPTODOK 653 



Measurements. 



M. 



Length of molars from second to fifth, inclusive 026 



Length of diastema 0037 



Length of base of Pm. ii 005O 



Length of Pm. iv 0070 



Width of Pm. iv 0050 



Length of M. i 0070 



Width of M. i 0050 



Depth of ramus at Pm. ii 0126 



Found on Cottonwood Creek, Wyoming. From the Bridger epoch. 



HEPTODON Cope. 



American Naturalist, 1882, p. 1029. Pachynolophus "Pom." Cope, Proceeds. Amer. Philos. See, 1881, 



p. 381, (not Pomel). 



? 1 4 3 



The dental formula is, I. -; C. - ; Pm. -; M. -. There is in both 



o 1 3 o 



jaws a considerable diastema between the canine and the anterior premolar, 



as well as one anterior to the canine. The inferior premolars diifer from 



the true molars, and the last of the latter has a fifth lobe or heel. This 



genus is in fact Lopliiodon with seven superior molars. 



The type of the genus is H. ventorum. It is only in this species that 

 the maxillary dentition is known; I associate in the same genus two similar 

 species known from the inferior dentition. I suspect that the Hyrachyus 

 singularis Cope, from the Wasatch epoch of New Mexico, belongs to this 

 genus. It is much smaller than the P. calciculus, which in turn is smaller 

 than the P. ventorum. 



1 originally employed Pomel's name PachynolojjJms for this geilus. 

 Professor Kowalevsky's figures and descriptions^ show plainly that the 

 genera are distinct, that genus being one of the Chalicotheriidce, and allied 

 to Latnbdotherium. 



'Monographic der Gutting Anthracotherium, Palaeontographica, XXII, p. 207, 1873. The ex- 

 ternal lobes of the superior molars are suhequal and are separated by a vertical rib. The transverse 

 crests are more or less complete. To this genns Professor Gaiidry (Enehainenients du Monde Animal), 

 refers the Propalmotherium of Gervais, which was founded on Pachynolophus isaelaims, in 1849. Packy- 

 nolophus bears date 1847. The European species are the following : 



I. Posterior cross crest of superior molars interrupted. P. duvali (type) ; P. eideroHHoua. 

 II. Posterior cross crest ©f superior molars continuous. P. argenionicua ; P. iaaelanus. 



