37 



having a partial investment of enamel, and with certain pecu- 

 liarities of cranial structure : the name TOXODONTIA is pro- 

 posed for this order, all the representatives of which are 

 extinct 1 . 



A second remarkable order, most of the members of which 

 have also passed away, is characterized by two incisors in 

 the form of long tusks ; in one genus (D mother ium) projecting 

 from the under jaw, in another genus (Eleplias) from the 

 upper jaw, and in some of the species of a third genus (Masto- 

 don) from both jaws. There are no canines : the molars are 

 few, large and transversely ridged ; the ridges sometimes few 

 and 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 : from this peculiar organ 

 is derived the name PEOBOSCIDIA given to the order. The feet 

 are pentadactyle, but the toes are indicated only by divisions of 

 the hoof; the placenta is annular; the mammas are pectoral. 



Elephants are dependent chiefly upon trees for food. One 

 species now finds the conditions of its existence in the rich 

 forests of tropical Asia ; a second species in those of tropical 

 Africa. Why, we may ask, should not a third be living at 

 the expense of the still more luxuriant vegetation watered by 

 the Oronoko, the Essequibo, the Amazon, and the La Plata, 

 in tropical America ? Geology tells us that at least two kinds 

 of Elephant (Mastodon Andium and Mast. Humboldtii) for- 

 merly did derive their subsistence, along with the great Mega- 

 therioid beasts, from that abundant source : two other kinds 

 of Elephant (Mastodon ohioticus and Eleplias texianus] existed 

 in the warm and temperate latitudes of North America. Twice 

 as many species of Mastodon and Elephant, distinct from all 

 the others, roamed in pliocene times in the same latitudes of 

 Europe. At a later or pleistocene period, a huge elephant, 

 clothed with wool and hair, obtained its food from hardy trees, 

 such as now grow in the 65th degree of north latitude ; and 



1 Philosophical Transactions, 1853, p. -291. 



