422 REPTILIA— ORDER HI.—SQUAMATA. 



channel, the section to which this genus belongs is technically known as the 

 Aglypha. And this fact alone is sufficient to indicate that all the members of 

 the section are innocuous. It will be superfluous to point out all the 

 characteristics by which the water-snakes differ from their immediate allies- 

 more especially as many of these are deep-seated, and require a considerable 

 amount of anatomical knowledge for their proper apprehension. It may be 

 mentioned, however, that teeth are present throughout both the upper and 

 lower jaws, and that those in the hinder part of the upper series exceed in 

 size those near the muzzle, while all those in the lower jaw have approxim- 

 ately the same dimensions. The relatively large eye has a circular pupil, 

 the scales are arranged in regular series running lengthwise, and between 

 the openings'of the nostrils are placed a pair of internasal shields. 



Of water-snakes there are forty or fifty species ; and the range of the 

 genus embraces the greater portion of the globe, with the exception of 

 South America and Australia south of the tropic. The species are, however, 

 less numerous in Africa than in the other countries of the Old World. All 

 are fond of water, in which they swim w ell, and their favourite haunts are 

 damp situations where access to a river or pond is easy. They live on frogs 

 and other small animals, which are seized in the mouth and swallowed as 

 rapidly as possible, without being killed by crushing in the folds of the body. In 

 addition to the ringed snake, several other species of the genus inhabit Europe. 

 Another familiar European species is the smooth snake {CoroneUa Icevis), 

 which belongs to a rather large genus. The so-called fierce snakes (Zamenis) 

 are also well represented on the Continent, among such being the dark green 

 snake {Z. ficvioiiensis) and the horseshoe-snake (Z. hippocrepis). To the same 

 genus bekmgs the well-known Indian rat-snake {Z. mucusus). Although 

 many or all of the foregoing will at times ascend trees in search of their prey, 

 the section includes others which are truly arboreal, and in coloration re- 

 semble the foliage among which they dwell. Such are the American wood- 

 snakes of the genus Herpetodryas, and their Old ^N'orld cousins included in 

 the genera Jjendropliis and Dcitdrclaphis. In all these, the eyes are pro- 

 portionally much lai-ger than in the water-snakes, and the body is more 

 or less strongly compressed. Some are remarkable for being able to change 

 the colour of their skin to harmonise with their surroundings after the manner 

 of the chamselcons and certain lizards. Far more interesting than any other 

 member of the family is the small South African egg-eating snake (Vasypeltis 

 sciibra). It may well be asked how a snake, with its long pointed teeth, 

 manages to seize and swallow the eggs of birds without losing their savoury 

 contents. And if the egg-eating snake had the ordinary dental armature, it 

 would doubtless find this a very difficult task. But special arrangements 

 have been made to suit its particular diet. Whereas teeth are wanting in the 

 fore part of the jaws, the upper surface of the throat is provided with a long 

 series of tooth-like organs formed by the elongation of the lower spines of tlie 

 joints of the backbone, which project through the membranes into the 

 throat. Taking an egg into the nearly toothless mouth, the snake gradually 

 passes it downwards into the throat, where it is split by the pressure of the 

 mill-like teeth, and its contents safely swallowed. Althougii this snake is a 

 very small creature, it will at a pinch cram a hen's egg into its mouth, when 

 it looks somewhat like a football with a tail to it. How it manages to force 

 such a huge object into its throat, and still more, how it cracks it when once 

 there, we arc not told. 



The second section into which the family Culahrid/.K is divided takes its 



