RUMINANTIA. 245 



They have only three toes to the hind-feet ; the canines do not project ; 

 they have no tail. Their raetacarpal and metatarsal bones are soldered 

 together as in ruminants, and their stomach is also divided into several 

 sacs, presenting a marked analogy to that family. 



To this division of the Ungulata belong some remarkable fossil 

 genera ; viz., Palceotherium, Anoplotlierium^ &c. The former somewhat 

 resembled tapirs, and the latter presents, according to Cuvier, most 

 singular relations with the different tribes of Pachydermata, approxi- 

 mating in some respects to the order Ruminantia. Their teeth form a 

 continuous series, without any intervening space, a disposition seen 

 elsewhere in man only. 



The family Hippopotamidce contains one genus only, the Hippopotamus, 

 with one or two species. They are huge unwieldy animals, with im- 

 mense heads, four incisors in each jaw, those of the lower one projecting ; 

 large canines, especially the lower one, and six or seven molars on each 

 side above and below. They have four toes on all the feet, nearly equal, 

 and ending in small hoofs, a short tail, and small eyes and ears. Their 

 stomach is divided into several sacs. Their skin is naked, and they are 

 very aquatic in their habits. The common species is Hippopotamus 

 amphibius, L., and a second species has been lately made known, 

 //. liberieusis, Morton, distinguished generically by Leidy as Chceropsis. 



Tribe KUMINANTIA. 



Feet with two toes with hoofs, and two supplementary hoofs in many. 

 Upper incisors generally wanting, six or eight (apparently) in the lower 

 jaw canines in the upper jaw sometimes present : four stomachs. 



The camels alone, of all the ruminating animals, have incisors in the 

 upper jaw. In all other they are completely wanting, their place being 

 supplied by a hardened and somewhat callous gum. The incisors have 

 simple trenchant crowns, slanting forwards. The outermost of the lower 

 incisors, when more than six, are the representative of the canines, and 

 there are besides upper canines in a few. There is generally a wide space 

 between the incisors and molars. The molars are almost always six in 

 number on each side, above and below, and their crowns are marked by 

 double crescentic ridges of enamel. The crowns of the prsemolars are 

 smaller and less complicated than those of the true molars, which are 

 of a quadrilateral form with a somewhat convoluted margin. 



