CAINOZOIC AGE 



OLIGOCENE PERIOD 



INVERTE- Beyond the fact that it showed a decidedly closer resem- 

 BRATES blance to that now existing, there is little caUing for remark 

 asto the condition of invertebrate life. The gastropods or sea- 

 snails with the breathing apparatus, initiated in the Trias, 

 were greatly increasing their predominance over species of 

 older fashion. In coral life ancestral forms of some very 

 important reef-builders of the present day made their ap- 

 pearance (Madrepora). Coin-like nummulites — multitudi- 

 nous in Eocene times — were now being called in. 



There is nothing of particular note to report either about 

 AMPHIBIANS fishes or reptiles. In amphibian life, the frog fraternity 

 was diversified by the rise of forms closely related to 

 the Indian bull-frog (R. tigrina). And small toads — prob- 

 ably of the green kind — were by this time attesting 

 the successful development of tailless amphibians (Bufo 

 viridis). 

 MARSUPIALS Marsupials were still represented in Europe by opossums 

 {Didelfhys) ; but there is not much evidence as to " pouched " 

 life in other parts of the world. 



The higher mammal life had lost some of its quaint and 

 primitive features. The variously related Phenacodi had 

 become extinct ; and Lophiodonts and Palseotheres — with 

 affinities to horses, tapirs, and rhinoceroses — were passing 

 away, having, as it were, shot their bolts. 

 ANCYLOPODS But the days of strange beasts were far from being at an 

 end. Among other such creatures some hy^na-shaped brutes, 

 toothed like hoofed animals, but with clawed feet, were at 

 this time enjoying life in parts of Europe and North America 



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