ir. VERTEBRATA: MAMMALIA, CHIROPTEBA. 



637 



Fig. 661— Skull of Son'.c (From 

 Ludwig-Leunis.) 



the rudimentary condition or occasional absence of the canines 

 {Talpa |}-|t. ni'iny shrews f-?, j|). There is great variability in 

 the matter of replacement of teeth; in the shrews,, for instance, 

 the milk dentition is snpjiressed and 

 tlie second only is functional, while in 

 the hedgehog one incisor and one pre- 

 molar in each jaw, a second jiremolar 

 and the canine of the lower jaw func- 

 tion in both dentitions. In many re- 

 spects the insectivores resemble the 

 rodents: a clavicle is present; there are usually five toes furnished 

 with claws; there is a uterus bicornis, often divided its whole 

 length, and discoidal jjlacenta. 



Aside from the proboscis-like snout the insectivores resemble the 

 rodents in appearance, forming parallel groups to those of that order. 

 The ERINACID.E, or hedgehogs, of the Old World are spined like the porcu- 

 pines ; the SoRiciD^, or shrews {8orex* Blai-ina*), are mouse-like, as are 

 the allied Talpid^, or moles (Scalops,* Comlylura,* star-nosed mole), 

 which burrow in the earth and have the eyes more or less rudimentary. 

 Some authors place here Oaleopitltecus of the East Indies, which has a 

 similar membrane and similar sailing powers as the tlying squirrels. It 

 also presents resemblance to the bats and to the lemurs. The earliest 

 known insectivores date from the eocene. 



Fig. 662.— Skeleton ot bat. (After Brehm.) 



Order III. Chiroptera. 



The bats are the only mammals which actually fly, and this at 



once characterizes them. The flying membrane (patagium) is a 



thin fold of skin, richly supplied with nerves, which begins at the 



