ERA. AGE OF MAMMALS. 373 



4. Only very recently a remarkable American locality 

 lias been discovered. At Florissant, Colorado, a fresh- 

 water deposit of Upper Eocene or Lower Miocene age has 

 been found, one layer of which is black with the remains 

 of insects of all kinds. Scudder has identified more than 

 a thousand species. We give here (Fig. 336) a beauti- 

 fully preserved butterfly from this locality. Here, then, 

 we have phenomena like those at Oeningen,, and explained 

 in the same way. 



Fishes. In general appearance, Tertiary fishes are 

 much like those of the present day. Then, as now, Tele- 

 osts vastly predominated (Fig. 337), and Ganoids were 



PIG. 337. Tertiary fishes Teleoste : Lebias cephalotes, Miocene. 



nearly extinct. Then, as now, sharks were among the 

 chief rulers of the seas. In fact, they seem to have cul- 

 minated in the Tertiary. The Eocene strata of the At- 

 lantic border are in places full of sharks" teeth, some of 

 which are of incredible size. We have seen one of these, 

 of the kind represented in Fig. 338, which would more 

 than cover a page of this book, being nearly seven inches 

 long and six inches wide. The original possessors of such. 



