274 LAND MAMMALS IN THE WESTERN HEMISPHERE 



graphical position, the Wind River fauna was largely transi- 

 tional between that of the Bridger above and that of the 

 Wasatch below. Unfortunately, the fossils are far less numer- 

 ous than those of the Bridger and not so well preserved, and 

 therefore give us a less adequate conception of the life of that 

 time. The archaic, non-progressive orders were strongly 

 represented, but already the progressive groups were in a numer- 

 ical majority of species ; most of these archaic orders may be 

 most advantageously described in connection with the Wasatch. 

 Opossums were almost certainly present, though the available 

 specimens are too fragmentary for assured determination. 

 The ftillodonts, ftseniodonts and insectivores differed little 

 from the Wasatch representatives of these orders, except that 

 the Bridger ftseniodont, '\Stylinodon, which had rootless, 

 persistently growing teeth, was associated with the Wasatch 

 genus \Calamodo7i. On the other hand, the primitive flesh- 

 eaters, or fcreodonts, which were referable to Wasatch families, 

 were less numerous and varied and formed a mixture of Bridger 

 and Wasatch genera. The fOxysenidse, the family with cat- 

 like teeth and head, had both the smaller Wasatch genus 

 ]OxycEna and the very large Bridger ]Patriofelis. Of the 

 blunt-toothed fMesonychidae, one very large animal {]Pachy~ 

 cena) survived from the Wasatch. The small forms of the 

 family fHysenodontidse were common, and there were numerous 

 species of the progressive family fMiacidse. 



Among the hoofed animals there were two of the antique 

 orders which became extinct before the end of the Eocene, 

 indeed, one of these groups, the fCondylarthra, made its 

 last appearance in the Wind River. This extremely primitive 

 group, which, in a sense, connected the hoofed with the clawed 

 mammals, will be described under the more ancient faunas. 

 The other order, the fAmblypoda, was represented by two 

 very different famihes, one of which, the f uintatheres, was 

 SO flourishing in the Bridger, where it formed the most char- 

 acteristic and by far the most striking element of the fauna. 



