70 TEXT-BOOK OF ZOOLOGY 



7. The velvety fur consists of short, close-set hairs, by which — 



(a) Dust and water are prevented from penetrating to the skin. 

 (Illustrate by dipping a velvet rag in water.) 



(b) As the hairs are not disposed in a particular direction, the fur is 

 always smooth, and in consequence the animal is not hindered in its 

 movements, whether these be directed forwards or backwards. 



(c) When we reflect that all animals living in complete darkness are 

 colourless (larva of cockchafer, tape-worm), the black fur of the mole 

 must appear surprising. The mole, however, is not exclusively subter- 

 ranean in its habits, for at night it comes to the surface in pursuit of 

 eartb-worms and insects, and while thus occupied is rendered almost 

 invisible by its dark coat. 



8. External ears, which would impede the animal's progress in its 

 underground passages, are absent. They are not required for the 

 purpose of catching sound, seeing that the soil is a much better 

 conductor of sound than air, and because the whole body of the animal 

 acts as an external ear. The animal perceives the vibrations of the soil 

 in the form of sound waves, as we do those of the air. (Experiment : 

 Stop up your ears so that you can no longer hear the ticking of a watch ; 

 now take the watch between your teeth. What do you observe ?) The 

 openings of the ear-passages can be closed to prevent the entrance of sand 

 or earth. 



9. The nostrils at the end of the snout are directed downwards for 

 the same reason (against ingress of sand, etc.). 



10. The upper lip is not rounded as, e.g., in man, but provided with a 

 cutaneous fold, which is applied to the lower lip. In this way the mouth 

 is firmly closed. (People who are obliged to work much in dusty air are 

 in the habit of fastening a cloth over the mouth.) 



11. The eyes, which are not larger than a poppy-seed, are completely 

 hidden in the thick fur, and useless to the animal. In its dark subter- 

 ranean domain there is, indeed, nothing to be seen, and large well- 

 developed eyes would be superfluous. 



B. Structure of Body, and Food. 



1. Dentition. — A glance into the open mouth of the mole at once 

 convinces us of its carnivorous habit ; indeed, as a naturalist has 

 expressed it, it is " more carnivorous than the cat or the dog." The 

 canine teeth resemble sharp-pointed daggers, and the crowns of the 

 molars are divided into sharp tubercles, arrangements which indicate 

 that (as in the bat) its food must consist of insects and insect larvae. It 

 also makes great havoc among mice, and consumes with equal relish 

 frogs and toads, earth-worms and snails. 



