UNGULATA. 351 



the four crescentic cusps, no intermediate tubercle. The angle of the 

 mandible is considerably produced downwards and backwards. The genus 

 is restricted to the Lower Pliocene (Siwalik Formation) of India, and the 

 typical species, M. dissimilis, has a skull about 0'4 in. in length. There is 

 also a dwarf species, M. nanus. 



Some of the later Eocene buno-selenodonts of the western 

 European area are remarkable for the possession of three 

 well-developed digits on each foot. These digits are a little 

 spreading, and are supposed by some to have been originally 

 connected with a web. The animals thus characterized are 

 grouped together in the family Anoplotheriidse, which had 

 a remarkably restricted range both in space and time, and 

 does not appear to have left any descendants. The typical 

 genus is Anoplotherium, while Diplobune and Dacrytherium are 

 associated and closely allied forms. 



FIG. 201. 



Anoplotherium cayluxense ; right upper molars 13, premolars 3, 4, nat. size. 

 U. Eocene (Phosphorites) ; Quercy, France. (After Lydekker.) 



Anoplotherium (fig. 201). This genus was first described by Cuvier, 

 and thus named in allusion to its lack of all defensive weapons, whether 

 tusks, horns, or claws. The skull is elongated, with a short and small 

 cranial region, and the basicranial axis straight. The orbit is relatively 

 small, and not completely separated by bone from the temporal fossa. 

 The dentition is complete, with the usual 44 teeth, all in regular close 

 series, approximately equal in height, not even the canines differing from 

 the others in development. The upper molars (fig. 201) exhibit a supple- 

 mentary fifth cusp between the ordinary two anterior cusps. The hinder- 

 most lower molar is produced into a third lobe posteriorly. The dorso- 

 lumbar vertebrae are proved to be 19 in number, as usual in artiodactyls ; 

 but the tail is exceptional in being very much elongated and provided 

 with chevron bones. The animal may have inhabited swamps and marshes 

 and employed the tail in swimming. The radius and ulna are complete, 

 separate, and about equally stout ; the fibula is also complete and separate, 

 but relatively slender. In each foot the two principal digits (nos. in and 



