688 MAMMALIA [CH. 



arm and leg runs down through the centre of the third finger or toe 

 (Fig. 344), and (2) the ARTIODACTYLA, in which there is an even 

 number of toes, and in which the axis of the limb passes down 

 between the third and fourth toes (Fig. 347). 



Division I. PERISSODACTYLA. 



The Perissodactyla were formerly a numerous class of animals, 

 but now three families alone survive, the Tapirs, TAPIRIDAE; 

 the various species of Rhinoceros, RHINOCEROTIDAE ; and the Horse 

 and numerous species of Ass, EQUIDAE. 



Of these the oldest and most primitive are the TAPIRIDAE. They 

 still have four toes on the fore-feet, which is an even 

 number ; but as they have only three on the hind-feet 

 and in both fore- and hind-feet the axis of the limb runs through the 

 third toe, there is no doubt that they are to be classed with the Peris- 

 sodactyla (Fig. 344). The snout is long and flexible, longer than 

 the snout of the Insectivores but not so long as the snout of the 

 Elephant. A most interesting feature in the natural history of the 

 Tapirs is that they are now found only in two widely separated parts 

 of the world, viz., the north of South America and in the Malay 

 Peninsula with the neighbouring islands of Borneo and Sumatra. 

 We need not however suppose that there was at one time a land 

 bridge across the Pacific, for in Eocene rocks we find remains of- 

 Tapirs all over Europe, Asia and America, so that the present 

 species are to be regarded as two separated remnants of a great race 

 of animals which once had a very wide distribution. Their present 

 range affords an often quoted example of what is known as "dis- 

 continuous distribution." 



The RHINOCER'OTIDAE are represented at the present day by the 

 genus Rhinoceros. The Rhinoceros is a heavier and 

 clumsier animal than the Tapir; it has three toes on 

 both fore- and hind-feet and no projecting snout. 

 Its chief peculiarity however is the horn which it carries so to speak 

 on the bridge of its nose. The horn has no bony core, and as it is 

 entirely composed of horny matter may be said to be a mass of 

 hairs stuck together. There are several species found in Asia 

 and in Africa ; the best known is perhaps the Indian, R. unicornis 

 (Fig. 345); the Javan, R. sondaicus, is smaller. Both these species 

 have but one horn. Two-horned Rhinoceroses (the two horns stand- 

 ing one behind the other) are now found in the Malay Peninsula, 



