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TEXT-BOOK OF ZOOLOGY 



to which it bears a strong general resemblance (see above). The viper 

 is, however, most easily recognised by the peculiar marking (" the sign 

 of Cain"), viz., the dark zigzag band which runs from the neck down 

 the back to the tail, and also by the dark H- or X-shaped mark on the 

 head. The ground colour of the back is very variable : grey, greenish, 

 brown, reddish-brown, in boggy places even black, but always corre- 

 sponding very markedly to the colour of the soil of its habitat. (What 

 is the importance of this correspondence of colours ?) 



B. Habitat. 



The viper is met with everywhere : on mountains and plains, in 



meadows or fields, 

 on marshes and 

 heaths, and in 

 woods. It resides 

 in holes in the 

 ground, or similar 

 recesses, in which 

 it also spends the 

 winter (why is it 

 obliged to hiber- 

 nate?). During 

 the daytime it lies 

 hidden in its re- 

 treat, or basks idly 

 in the warm sun- 

 shine (why?). 



C. Pursuit of 

 Prey. 



This is not 

 commenced until 

 nightfall. The 

 viper feeds principally on mice, which it pursues into their holes (its 

 shape is adapted for this). The young (which are brought forth alive) 

 live on small lizards. 



(a) The pupil of the eye is vertical and very dilatable, characters 

 indicative of a nocturnal habit (compare with cat). 



(b) The maxillary bones are very short, in fact rudimentary, and in 

 addition to the poison fangs, which are as brittle as glass, carry no other 

 hook-teeth (see ringed snake). The viper, therefore, would be unable 

 to retain a hold on its struggling prey. Accordingly, it kills the latter 



HEAD AND ANTERIOR PORTION OF THE BODY OF THE VIPER. 

 G., Poison fang ; E., reserve fang. 



