ORDER INSECTIVORA ; GENERAL CHARACTERS. 195 



yet they all agree in having the teeth raised into conical and 

 pointed tubercles, for the purpose of crushing the hard envelopes 

 of their insect prey. They agree also, in being for the most part 

 nocturnal animals ; and, with some exceptions, in living under- 

 ground, or at least in exhibiting a tendency to such a mode of 

 life ; and all those which inhabit cold countries pass the winter 

 in a state of torpidity. They are timid little creatures; and 

 although constantly at work around us, and in a manner most 

 important to our welfare, their habits are so unobtrusive as to 

 escape our observation. They are especially appointed to check 

 the overwhelming increase of the worm and insect tribe, and 

 especially of those species which live beneath the soil ; the 

 ravages of which, if not thus kept within bounds, would be 

 speedily destructive to man and beast, by preventing the growth 

 of those vegetables on which they depend for food. Their general 

 conformation varies according to their mode of life ; but they 

 agree in the possession of clavicles, and in the application of the 

 sole of the foot to the ground ; and their limbs are generally 

 short. The order may be divided into four families ; which 

 are characterized by their habits, as well as by their external 

 form and internal structure. 1. The TALPID.E, or Mole tribe, 

 which are pre-eminently subterranean, and are distinguished by 

 their extraordinary habit of forming long complicated burrows 

 underground, in which they are born, and in which they pass 

 their whole lives, feeding, hybernating, breeding, and dying, 

 in these subterranean retreats. 2. The SORICID^;, or Shrew 

 tribe, which are a sort of carnivorous mice ; these, although 

 they do not actually burrow, retreat during the winter, and for 

 their ordinary repose, into holes ; they feed, however, on the 

 surface and in the water, several of them being purely aquatic, 

 diving with facility after aquatic insects, and remaining a long 

 time under water without inconvenience. 3. The ERINACEAD^, 

 or Hedgehog tribe, contains animals which do not burrow or 

 descend into deep excavations ; but which conceal themselves 

 during hybernation beneath a covering of leaves, or in some 

 superficial hollow ; and which live upon food that they find 

 either upon or near the surface. These are further characterised 



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