282 



ANATOMY OF VEKTEBRATES. 



locomotion, the Ungulata have no clavicles ; the fore-leg is prone : 

 the molar teeth are massive, with inflected folds of enamel: they 

 feed on vegetables. 



A remarkable order, most of the members of which have passed 

 away, is characterised by two incisors in the form of long tusks ; 

 in one genus {Dinotlieriurn) projecting from the under jaw, in 

 another genus {Eleplias) from the upper jaw, fig. 162, i, and 

 in some of the species of a third genus (^Mastodon) from both 

 jaws. There are no canines; the molars are few, large, and 



162 



Skeleton of Elephant (Elephas Indiais) 



transversely ridged, fig. 161, the ridges sometimes few, some- 

 times mammillate, often numerous and with every intermediate 

 gradation. The nose is prolonged into a cylindrical trunk, 

 flexible in all directions, highly sensitive, and terminated by a 

 prehensile appendage like a finger, fig. 162, 7i : on this organ is 

 founded the name Proboscidia given to the order. The feet 

 are pentadactylc, but the digits are outwardly indicated only by 

 divisions of the hoof; the testes are abdominal ; the placenta is 

 annular ; ' the mamma? are pectoral. 



' Besides the annular placenta there is a subcircular villous patch at each pole of 



