258 THE HISTORY OF CREATION. 



and in certain hoofed Rodentia (Subungulata) which live 

 exclusively in South America. Beside smaller forms (for 

 example, guinea pigs and gold hares) the Subungulata also 

 include the largest of all Rodentia, namely, the Capybara 

 Rats, which are about four feet in length. The Rock Conies, 

 which are externally very nearly akin to Rodents, especially 

 to the hoofed Rodents, were formerly classed among 

 Rodentia by some celebrated zoologists, as an especial sub- 

 class (Lamnungia). Elephants, on the other hand, when not 

 classed among Hoofed animals, were generally considered 

 as the representatives of a special order which were called 

 Trunked animals (Proboscidea). But the formation of the 

 placentas of Elephants and of Hyrax agree in a remark- 

 able manner, and are entirely distinct from those of Hoofed 

 animals. These latter never possess a decidua, whereas 

 Elephants and Hyrax are genuine Deciduata. Their placenta 

 is indeed not of the form of a disc, but of a girdle, as in 

 the case of Animals of Prey ; it is very possible that the 

 girdle-shaped placenta is but a secondary development of 

 the discoplacenta. Thus, then, it might be thought that 

 the Pseudo-hoofed animals have developed out of a branch 

 of the Rodentia, and in a similar manner perhaps the 

 Camivora out of a branch of the Inseetivora. At all 

 events. Elephants and Hyrax in many respects, especially 

 in the formation of important skeletal parts, of the limbs, 

 etc., are more closely allied to the Rodentia, and more 

 especially to hoofed Rodentia, than to genuine Hoofed 

 animals. Moreover several extinct forms, especially the 

 remarkable South American Arrow-toothed animals (Toxo- 

 dontia), stand in many respects mid- way between Elephants 

 and Rodentia. That the. still living Elephants and Hyrax 



