554 MANUAL OF ZOOLOGY. 



Hares, Rabbits, Squirrels, and others, characterised by the 

 absence of canines and the possession of no more than two 

 incisors in the lower jaw, and usually no more than two in the 

 upper jaw. The incisors are greatly developed, growing from 

 permanent pulps, and continuing to grow during the life of the 

 animal. Placenta deciduate and discoidal. 



Order XI. Cheiroptera, comprising only the various Bats, 

 and characterised by the fact that the four outer or ulnar 

 fingers are greatly developed and elongated, and are united 

 together by a leathery flying-membrane or " patagium," which 

 is continued from the hand and arm to the side of the body 

 and hind-limb. By means of this patagium the Bats possess 

 the power of flight. Clavicles are always present. The teeth 

 vary a good deal, but there are always canines. The placenta 

 is deciduate and discoidal. 



Order XII. Insectivora, comprising the Moles, Shrew-mice, 

 and Hedgehogs, characterised by having the crowns of the 

 molar teeth furnished with sharp and pointed cusps. Well- 

 developed clavicles are present in almost all cases. The pla- 

 centa is deciduate and discoidal. 



Order XIII. Quadrumana, comprising the Lemurs, Apes, 

 and Monkeys. Dentition usually the same as in man, or with 

 an additional praemolar on each side of each jaw, or varying a 

 good deal in the lower forms. The series of teeth is uneven 

 and interrupted. The innermost digit of the fore-limb (pollex) 

 is mostly opposable to the other fingers when present, but it 

 may be wanting. The hallux is also opposable to the other 

 toes of the hind-limb, so that the hind-feet constitute prehen- 

 sile hands. Clavicles are always present. The placenta is 

 deciduate and discoidal. 



Order XIV. Bimana. This order includes Man alone. The 

 dental formula is 



. 2 - 2 I - 1 2 - 2 ^ - T. 



The teeth are nearly even, and are not interrupted by any 

 interval (diastemd). The pollex or thumb of the fore-limb is 

 opposable to the other digits, but this is not the case with the 

 hallux or great toe. The attitude of the body in progression 

 is habitually erect. The placenta is deciduate and discoidal. 



