582 ZOOLOGY. 



Insectivora, and bats should be associated with the Edentates 

 in Bonaparte's division (or, as Gill terms it, super-order) 

 of Ineducdbilia (which corresponds to Owen's sub-class 

 Lissencephala). In these four orders, then, the cerebrum is 

 small, smooth, with none or few convolutions ; in front 

 it does not cover the olfactory lobes, and behind leaves 

 the cerebellum wholly or partly uncovered. 



On the other hand, in the super-order Educabilia, com- 

 prising the following orders : Cetacea, Sirenia, Proboscidia, 

 Hyracoidea, Toxodontia, Unyulata, Ferce, and Primates, 

 the brain has a relatively large cerebrum, behind overlap- 

 ping much, or all, of the cerebellum, and in front much, or 

 all, of the olfactory lobes (Gill). The cerebrum is also con- 

 voluted ; the convolutions increasing in number and com- 

 plexity, until we reach the apes and man, and accompanied 

 by increasing intelligence and capability for mental im- 

 provement. Other important characters are mentioned by 

 Owen and by Gill in support of this arrangement. 



In the smooth small cerebrum, as well as in other re- 

 spects, the Ineducdbilia are related, together with the mar- 

 supials and duckbill, to the birds and reptiles. In the 

 cloaca, the convoluted trachea, the long, slender, beak-like, 

 toothless jaws and the gizzard of the ant-eaters, the quills 

 of the porcupine and hedge-hog, the proventriculus or crop 

 of the dormouse and beaver, in the growing together of the 

 three chief metatarsals of the jerboa, as in birds, in the keeled 

 sternum and wings of the bats, there are points of resem- 

 blances to birds. Owen, whom we have quoted, also adds 

 the aptitude of the bats, insectivores and certain rodents 

 "to fall, like reptiles, into a state of torpidity, associated 

 with a corresponding faculty of the heart to circulate car- 

 bonized or black blood." 



However, there are points in which these orders are re- 

 lated to the lemurs and monkeys. 



Order 2. Glires. (Rodentia.) The rats, squirrels, por- 

 cupine, and beaver are common examples of this extensive 

 group. They differ from other orders in the large incisors, 

 the dental formula of which is normally | (f in Leporidce 

 and Layoinyid(&), and in the absence of canine teeth. The 



