CHAPTER II 



EXTERNAL CHARACTERS— INTEGUMENT 



THE form varies enormously, worm-like in some, 

 comparatively short and heavy, elongate and 

 more or less slender, or extremely gracile and almost 

 filiform, in others. In this respect our common Grass- 

 snake occupies a central position, and for this reason 

 is termed a moderately slender form, anything above 

 or below this standard being described as com- 

 paratively short or elongate. Our shortest and 

 stoutest European Snakes are the Vipers, especially 

 Vipera ursinii ; our longest and slenderest, the Coluber 

 and Zamenis, especially Zamenis dahlii. These 

 extremes in both directions are, however, far sur- 

 passed by many exotic snakes, as we find on 

 comparing, for instance, one of the African Puff- 

 adders (Bitis), with certain Oxybelis and Leptognathus 

 from Tropical America. The body may be some- 

 what rigid, as in some burrowing and ground snakes, 

 not unlike in appearance to our Slow- worm and other 

 limbless Lizards; or extremely flexible, as in many 

 Pythons and Boas and in the Tree-snakes generally. 

 This flexibility may be accompanied by a vertical 

 compression of the body in relation with an arboreal 



existence, whilst sluggish snakes, such as most of the 



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