70 TERTIARY SERIES. 



series, it is to them principally that our present attention 

 will be directed. 



Mammalia of the Eocene Period. 



In the first great fresh-water formation of the Eocene pe- 

 riod, nearly fifty extinct species of mammalia have been dis- 

 covered by Cuvier ; the greater number of these belong to 

 the following extinct genera, in the order Pachydermata,* 

 viz., Palaeotherium, Anoplotherium Lophiodon, Anthraco- 

 therium, Cheropotamus, Adapis (see Plates 3 and 4.-|-) 



occasionally in the Miocene and Pliocene marine formations, e. g. m 

 Touraine and in the Sub-apcnnines. These are derived from carcasses 

 which, during these respective periods, were drifted into estuaries and 

 seas. 



No remains of mammalia have yet been found in the Plastic clay for. 

 mation next above the chalk ; the admixture of fresh-water and marine 

 shells in this formation seems to indicate that it was deposited in an es- 

 tuary. Beds of fresh-water shells are interposed more than once between 

 the marine strata of the Calcaire Grossier, which are placed next above the 

 plastic clay. 



* Cuvier's order Pachydermata, i. e. animals having thick skins, includes 

 three subdivisions of Herbivora, of which the Elephant, Rhinoceros, and 

 Horse are respectively examples. 



t Palasotherium. 



The place of the genus Palaeotherium (see Plates 3 and 4) is interme- 

 diate between the rhinoceros, the horse, and tapir. Eleven or twelve 

 species have already been discovered ; some as large as a rhinoceros, 

 others varying from the size of a horse to that of a hog. The bones of 

 the nose show that, like the tapir, they had a short fleshy trunk. These 

 animals probably lived and died upon the margins of the then existing 

 lakes and rivers, and their dead carcasses may have been drifted to the 

 bottom in seasons of flood. Some perhaps retired into the water to 

 die. 



Anoplotherium. 



Five species of Anoplotherium (see Plates 3, 4) have been found in the 

 gypsum of the neighbourhood of Paris. The largest (A. Commune) being 

 of the size of a dwarf ass, with a thick tail, equal in length to its body, 

 and resembling that of an otter; its probable use was to assist the animal in 

 swimming. Another (A. Medium) was of a size and form more nearly 

 approaching tlie light and graceful character of the Gazelle ; a third species 

 was nearly ot the size of a Hare. 



