MAMMALIA. 435 



mune also existed on tlie Isle of Wight. Another species is mentioned as 

 peculiar to the Sivalik Mountains in Asia. 



The genus Xiphodoii is composed of one species of Anoplotherium, the 

 light and slender form of which seems to indicate great agility, comparable 

 only to that of the gazelle and the roe. The tail is short and slender. 



The genus Dichobune, with the same essential characters, is of the size 

 of the hare, with the same proportion between the anterior and posterior 

 limbs, which according to all probability gave to them a similar walk. 

 Three species occur in the tertiary basin of Paris, and a fourth is peculiar 

 to Enoiand. 



The genus Oplotherium exhibits great af&nities with Anoplotherium, and 

 more especially with Dichobune, but differs by an essential character ; the 

 canines, which in the preceding genera are scarcely to be distinguished 

 from the incisors, are prominent and curved like those of the tapirs and 

 Paljeotherium. Species of this genus have been found in France and 

 Germany. The genus Microtherium was established upon one of them. 



The genus Macrauchenia combines in a remarkable manner the forms 

 of the camel and Palseotherium. The head and teeth are yet unknown ; 

 but the vertebrae of the neck indicate that this region of the body was 

 elongated, as in the lama. The legs or limbs resemble those in ruminants, 

 but the feet are constructed as in pachyderms. The only species know'n 

 was found in Patagonia, south of St. Julian harbor. Its size was nearly 

 equal to that of the rhinoceros and hippopotamus of our days. 



The genus Chalicotherium is known only by its dentition, whict indicates 

 an af&nity with Anoplotherium. Two species have been found in the 

 meiocene deposits of Germany, whose bulk, it is supposed, reached that of 

 the rhinoceros. 



The genus Cainotherium we merely mention here. It is but little known. 

 In the opinion of some it is the same as Chalicotherium, and in that of 

 others the same as Oplotherium. Two species, we are told, have been 

 found in the eocene deposits of France. 



Fam. 2. IliPPOPOTAMiDJE, or Pachydermata proper, in the actual fauna, 

 generally comprehends clumsy and colossal beings the limbs of which are 

 very short, the hind feet with three and the fore feet with three or four 

 hoofed toes. The hoofs themselves are of irregular forms, as in the follow- 

 ing family, and all of them rest on the bottom. For this reason there are 

 no posterior rudimentary toes. The dentition exhibits both analogies and 

 af&nities with the other families of the order. The incisors are either want- 

 ing or vary in number from two to six. Canines seldom exist, and where 

 they happen to be present their length is not disproportioned. The molars 

 are generally seven in each jaw, sometimes only six in the lower, exhibiting 

 various forms. The few living genera, with equally few species, inhabit the 

 warmer parts of both the old and new worlds. Fossil remains of species 

 belonging to the recent, genera, together with others belonging to genera 

 entirely extinct, have been found in the tertiary beds of America, Europe, 

 and Asia. 



The genus Hippopotamus is characterized by a very massive and naked 



639 



