ERA OF THE TERTIARY FORMATION. 



67 



names with reference to the proportions which they re- 

 spectively present of surviving species — first the eocene 

 (from 'yog, the dawn ; x aLV0C > recent ;) second the mio- 

 cene (uetwv, less :) third older pliocene (ttTieicjv, more;) 

 fourth, newer pliocene. 



EOCENE SUB-PERIOD. 



The eocene period presents, in three continental groups, 

 1238 species of shells, of which forty-two, or 3.5 percent., 

 yet flourish. Some of these are remarkable enough ; but 

 they all sink into insignificance beside the mammalian 

 remains which the lower eocene deposits of the Paris ba- 

 sin present to us, showing that the land had now become 

 the theatre of an extensive creation of the highest class of 

 animals. Cuvier ascertained about fifty species of those, 

 all of them long since extinct. A considerable number 

 are pachyderm at a ,* of a character approximating to the 

 South American tapir : the names palaeotherium, anthra- 

 cotherium, anoplotherium, lophiodon, &c, have been ap- 

 plied to them with a consideration of more oi less con- 

 spicuous peculiarities ; but a description of the first may 

 give some general idea of the whole. It was about the 

 size of a horse, but more squat and clumsy, and with a hea- 

 vier head, and a lower jaw shorter than the upper; the 

 feet, also, instead of hooves, presented three large toes, 

 rounded, and unprovided with claws. These animals were 

 all herbivorous. Amongst an immense number of others 

 are found many new reptiles, some of them adapted for 

 fresh water ; species of birds allied to the sea-lark, cur- 

 lew, quail, buzzard, owl, and pelican ; species allied to 

 the dormouse and squirrel ; also the opossum and ra* 

 coon ; and species allied to the genette, fox, and wolf. 



MIOCENE SUB-PERIOD. 



In the mioceno sub-period, the shells give eighteen per 

 cent, of existing species, showing a considerable advance 

 from the preceding era, with respect to the inhabitants of 

 the sea. The advance in the land animals is less marked, 

 but yet considerable. The predominating forms are still 



* Thick-skinned animals. This term has been given by Cuvier 

 to an order in which the hog, elephant, horse, and rhinoceros are 

 included. 



