530 



CENOZOIC ERA— AGE OF MAMMALS. 



Fig. 908.— Periptychus Rhabdodon : A, Hind-foot, x £ ; B, Hind-limb, x £ (after Osborn). 



5. Green River Basin — Wahsatch Beds — Lower Eocene. — Imme- 

 diately above the last, but still in the Lower Eocene, is found another 

 mammalian fauna equally abundant in species and equally remarkable, 



Fig. 909.— An almost perfect Skeleton of a Phenacodus primsevus (after Cope). 



but almost wholly different. From this fauna we select two, Phenacodus 

 and the Coryphodon (peak-tooth). The Phenacodus (Fig. 909) is 

 probably the most generalized mammal known. It may be regarded 



