182 HIGH SCHOOL ZOOLOGY. 



36. As far as regards the dentition, the Insectivora are 

 certainly the most primitive ; they are also all ])lantigrade 

 forms, and have well-developed clavicles. The teeth are not 

 more nnmerous than in the Carnivores, but the canine 

 tooth does not assume the function which it has in most 

 mammals, sometimes an incisor, sometimes a premolar, project- 

 ing further from the jaw than it does itself. Seven molars are 

 by no means always present, but their surfaces are always 

 tuberculate, in accordance with the insect-food. 



Between groups of Rodentia and Insectivoi^a, which corres- 

 pond in their habits, a certain superficial resemblance is to be 

 detected, a convergence of character which we attribute to the 

 influence of their sxirroundings, but the Rodents, as we shall 

 learn, including about one-third of all the species of mammals, 

 ofter a greater wealth of form than we find in the Insectivora. 

 To these two orders belong all the smaller species of Mammalia, 

 and, indeed, parallel groups of both orders are to be be found, 

 some adapted for a life on the surface of the ground, some for 

 burrowing underneath it, some for a semi-aquatic, and some for 

 a more or less completely arboreal life. 



Only two out of the six families are represented in our region, the 

 Shrews {Soricidce), and the Moles ( Talpidoi). The former are mouse-hke 

 Insectivora with an elongated muzzle, and a short velvety coat. In both 

 the common forms, the eyes are small, and in one (Sorex platyrhinus) the 

 ears and tail are long, while, in the other (Blarlna brevkauda), both are 

 short. Both of these are terrestial species, but an af^uatic genus 

 ( Myotjale), in which the toes are webbed and which has a very penetrating 

 musky odoui', is found in South-east Russia and the Pyrenees. In all, the 

 hinder feet are larger than the fore, ])ut, in the Talpidaj, the fore feet are 

 converted into broad shovel-like structures, with short toes and stout 

 claws for digging the burrows in which they live (Fig. 1 lOM); the limbs are 

 very short, the body elongated and cyUndrical in outline, the head very 

 small, without either evident eyes or ears. The shape of the body is ob- 

 viously adapted to the undei-ground life, and the snout is provided with 

 extremely delicate tactile sensibility. This is best seen in the Star-nosed 

 moles {Condijlura crisfaia), where tlie fleshy disc at the enrl is divided 



