Vol. 6] Merriam: Virgin Valley and Thousand Creek. 



261 



No. 

 10665 



irior diameter 24. 22 27.5 23. 



P 4 , transverse 

 M lT anteropost 



M„ transverse diamete Ivi 

 M 2 , anteroposterior 



M,, transverse 



H. 



H. 



H. 



No. 



No. 



osborni 



equina s 



affinis 



12587 



11760 



24. 



22 



27.5 



23. 





19.4 



14 



21. 



18.6 





23.8 



23 



28.5 



22 



22 2 



18.1 



14 



20. 



16. 



16.5 



23.5 



22 





21. 



21.8 



16.2 



12 





14.4 



15.4 



20.3 



25 







25. 



15. 



10 





13. 



13.2 



PARAHIPPUS, compare AVUS (Marsh) 



Several lower cheek teeth from Virgin Valley (figs. 29a to 

 29r) represent a species of Parahippus larger than Parahippus 

 crenidens of the Deep River Beds or P. brevidens of the Mascall, 

 but corresponding approximately in size to P. nebrascensis de- 

 scribed by Peterson 17 from the upper Harrison Beds. This 

 species should lie compared with the doubtful Parahippus avus 

 (Marsh) from the Mascall. 



Pigs. 29« to 29c. Parahippus, compare avus (Marsh). No. 39403, nat- 

 ural size. Pig. 29a, outer view; fig. 29b, occlusal view; fig. 29c, inner 

 view. Virgin Valley Beds, Virgin Valley, Nevada. 



The crowns of the lower cheek teeth are short and the enamel 

 is quite rough. On all of the specimens there is evidence of a 

 considerable covering of cement. On the outer side there is a 

 distinct shelf developed on the cingulum, and a small basal 

 tubercle is present between the protoeonid and hypoconid. The 

 metaconid and metastylid pillars are distinctly separated. The 

 entoconid pillar is also large and the entostylid is well developed. 

 The development of the metaconid, metastylid, and entoconid 

 pillars tends to narrow the inner ends of the anterior and pos- 

 terior valleys much more than in Hypohippus. A characteristic 



17 Peterson, O. A., Ann. Carneg. Mus., vol. 4, p. 57, 1906. 



