574 MANUAL OF NATURAL HISTORY. 



valleys of the Danube and the Rhone ; and the 

 lacustrine sands and marls of Auvergne ; and also 

 along the southern basis of the Hinirnalaya. 



I. EOCENE GROUP. 



This group constitutes the most ancient of the 

 tertiary formations. It is composed of marine and 

 fresh-water beds of blue and plastic clays, thin 

 beds of sand, and shingle mixed with lignite, &c. 

 Here we find about three and a half per cent, of 

 shells which belong to types of existing species. 



Several Quadrumana have recently been dis- 

 covered in strata of this epoch ; namely a Macacus 

 from the eocene sand of Kyson ; a tail-less monkey 

 or Gibbon (Hylobates) in the South of France ; 

 several species of Semnopitheci in India; and a 

 Callithrix in the basin of the Rio des Velhas, in 

 Brazil. The Mammals of the tertiary formations 

 were principally, however, ponderous vegetable- 

 eating quadrupeds, that loved to frequent the river- 

 banks, marshes, and borders of lakes ; such were 

 the colossal Mastodon, the lofty Sivatherium, the 

 thick-skinned Rhinoceros, the amphibious Hippo- 

 potamus, the long-nosed Tapir, and the Hog. 

 Among Cetaceous mammals, we here find the great- 

 headed Balcena, with its laminated whale-bone, 

 the Ztiphius and Balcenodon, with sharp, conical 

 teeth, and the Zeuglodon, a gigantic cetacean, 

 seventy feet in length. Ziphodon and Adapis are 

 pachyderms from the eocene stage, as is also the 

 singular Chceropotamus. 



