42 



BULLETIN UNITED STATES GEOLOGICAL SUKVEY. 



[YolY. 



The types which became extinct* with the close of each of these epochs 

 are the following : 



Loup Fork. 



BMnoceridm. 

 Hippotherium. 

 Stylonus. 

 OreodontidcB. 

 Equus Beds. 



Megatheriidce. 



Maclicerodus. 



Tapiridce. 



Elephas. 



Camelidce. 



Wasatch. 



Gastornithidce 

 Fantodonta. 



Baenidce. 

 Tillodonta. 

 Mesodonta. 

 Froviverra. 

 Dinocerata. 

 White Eiver. 

 Leptictidce. 

 Sycenodon. 

 Chalicotlieriidce. 

 Hyopotamidce. 



The above table exhibits the present state of our knowledge : it will 

 doubtless be much extended by future discovery, but not otherwise mod- 

 ified. 



The numerous able writers on European vertebrate palseontology have 

 more frequently recorded the appearance of types in defining their 

 faunal divisions than their disappearance. The following table is com- 

 piled from the writings of Gervais, G-audry, Pomel, Filhol, Eenevier, 

 and others, but is not as complete as I would desire. 



* Tliis means, as already mentioned, the forms wMch left no direct successors in the 

 Nearctic and Palsearctic Faunae. 



