xiii PHYLUM CHORDATA 471 



and devoid of convolutions. ^The testes are situated in the groin, 

 and are not enclosed in a scrotum. The uterus is two-horned or 

 double. The placenta is deciduate and discoidal. 



Included in this order are the Moles (Talpidce), Shrews (Soricidce), 

 and Hedgehogs (Erinaceidce). 



ORDER 8. CHIROPTERA. 



Eutheria in which the pectoral limbs are modified to form 

 wings, the bones, more especially those of the second to the fifth 

 digits, being greatly elongated so as to support a broad web of 

 skin extending back to the hind-limbs. The sternum has a keel 

 for the attachment of the pectoral muscles, which play an im- 

 portant part in bringing about the movements of flight. The 

 ulna is vestigial ; the pollex is small, the remaining digits greatly 

 elongated. The hind-limb is rotated outwards, so that the knee 

 is directed backwards. There is a cartilaginous rod (calcar) 

 attached to the inner side of the ankle-joint and helping to support 

 a fold of skin (inter-femoral membrane) which extends from the 

 hind-limbs to the tail or caudal region of the body. The cerebral 

 hemispheres are smooth and do not overlap the cerebellum. The 

 dentition is complete, heterodont and diphyodont. The penis 

 is pendent ; the testes abdominal or situated in the groin. The 

 uterus is simple or two-horned (bicornuate) ; the placenta deciduous 

 and discoidal. 



Sub-order a. Megachiroptera. 



Large frugivorous Chiroptera with elongated snout, without 

 foliaceous appendages to the nose and ears, the second digit of the 

 manus terminating in a claw. The tail, when present, is not 

 enclosed in the inter-femoral membrane, but lies below it. The 

 crowns of the molar teeth are devoid of sharp cusps. 



This sub-order comprises the so-called Flying Foxes (Pteropus) 

 of tropical and sub-tropical parts of the Eastern Hemisphere. 



Sub-order b. Microchiroptera. 



Small, mostly insectivorous, Chiroptera with short snout, fre- 

 quently with foliaceous appendages of the nose and ears, the 

 second digit of the manus never provided with a claw. The tail 

 when present is enclosed in the inter-femoral membrane. The 

 crowns of the molar teeth are provided with sharp cusps. 



This sub-order includes all the ordinary Bats (Vespertilio and 

 other genera). 



ORDER 9. PRIMATES. 



Eutheria nearly all adapted to an arboreal life, the limbs being 

 prehensile owing to the pollex and hallux being more or less com- 



