42 MAMMALIA— ORDER III.—INSECTIVORA. 



correlation with the nature of their diet, the stomach of these bats 

 is narrowed and elongated into a tube-like organ. The common vampire 

 (Desmodns rufus), ranging from Central America to the south of Brazil, 

 measures about three inches in length, and has reddish-brown fur on the 

 upper parts. The second species (Diphylla ecaudata) is rather smaller, and 

 confined to Brazil. These bats attack animals by shaving away the upper 

 layer of the skin from some bare part with their incisor teeth, and then suck 

 up the blood as it oozes from the capillary vessels. 



ORDER III.-mSECTIVORA. 



Insect- Eating Mammals. 



The third order of Mammals comprises a large number of mostly small-sized 

 insectivorous species, structurally nearly allied to the bats, but with the fore- 

 limbs of normal structure. With the exception of the tree-shrews and a few 

 aquatic species, they are all more or less completely nocturnal in their habits ; 

 but the group as a whole is one by no means easy of definition. As a rule, 

 they have five toes to each foot, all of which are furnished with claws, and 

 neitlier the thumb nor the great toe is capable of being opposed to the other 

 digits. In walking the whole sole of the foot is applied to the ground, in 

 what is termed the plantigrade manner. The crowns of their short upper 

 molar teeth are surmounted by a number of minute, sharp cusps, which may 

 be arranged either in the form of a W or a V ; and the incisor teeth, of which 

 there are not less than two pairs in the lower jaw, are never chisel-like, but 

 the first pair is often larger than the others. The canines, or tusks, are very 

 generally not distinctly larger than the other teeth ; and there is never a 

 pair of scissor-like cheek-teeth like those characterising the terrestrial 

 Carnivora. Except in one or two species, perfect collar-bones are developed ; 

 and the lobes of the brain are nearly smooth, thus indicating very low 

 mental powers. Externally, Insectivores verj' generally have long slender 

 and narrow snouts, with the muzzle projecting considerably beyond the ex- 

 tremity of the lower jaw ; and while many of them are coated with fur, 

 which may be harsh and rough, others have a covering of spines, or spines 

 mingled with fur. 



As regards their geographical distribution, these Mammals present some 

 very curious features. In the first place, they are totally wanting in South 

 America, where their place is taken by the Marsupial opossums ; but they 

 are represented by a peculiar family, with one genus, in the West Indian 

 Islands. A more or less closely allied family occurs in Madagascar, where 

 there are also other peculiar types ; and tlie order is distributed over North 

 America and all the great continents of the Old World, although absent from 

 Australia and Papua. From geological evidence, coupled with its abundance 

 in Madagascar, the order is evidently an ancient one ; and its existing members 

 have probably been enabled to survive either by their small size ancf nocturnal 

 habits, their protective armour of spines, or from dwelling iu countries 

 where the larger Carnivora are either absent or but few in number, or by having 

 taken to a subterranean mode of life. Whereas the majority of tlie Insectivora 

 are terrestrial, the flying-lemurs are arboreal, and able to take flying leaps 



