2oo SNAKES. 



The large group of water-snakes bring us to the second and 

 by far the largest subfamily of the solid-toothed colubrines, which 

 is known as the Colubrince, and is distinguished from the preceding group by the 

 supratemporal bone not being produced over the region above the socket of the 

 eye ; while the scales are usually overlapping, and teeth are present throughout 

 the entire length of the upper and lower jaws. The water-snakes belong to a 

 large assemblage of genera of the subfamily characterised by the circumstance 

 that in the skeleton of the backbone inferior projections or spines are present 

 throughout its length, the vertebrae in the hinder region of the body having 

 these spines represented by a more or less well-developed crest or tubercle. 

 From their allies, the water-snakes are distinguished by having the hinder upper 

 teeth larger than those in front, the equality in the size of the lower teeth, the 

 rather large size of the eye, in which the pupil is round, the presence of a pair 

 of internasal shields between the nostrils, the regular longitudinal series formed 

 by the scales throughout the body, and by the teeth in each hinder upper jaw- 

 bone varying in number from eighteen to forty, and forming a continuous series. 



Represented by over forty species, the water-snakes have an almost cosmo- 

 politan distribution, although they are unknown in South America, while in 

 Africa south of the Sahara they are less abundant than in other regions, and in 

 Australia they occur only in the northern districts. Dr. Gimther writes that the 

 typical water-snakes " are easily recognised by their stoutish cylindrical body, 

 keeled scales, flat head covered with regular shields, wide cleft of the mouth, and 

 numerous teeth, the strongest of which are at the hinder end of the maxillary 

 bone. They frequent the neighbourhood of fresh water, and feed on aquatic 

 animals — frogs, toads, and fishes. They do not overpower or kill their prey by 

 throwing a coil of the body round it, but, having seized it, they at once commence 

 to swallow it. They are excellent swimmers, but more frequently live near water 

 than in it, in agreement with which habit, the position of their nostrils is not on 

 the upper surface of the head, as in the true freshwater snakes, but on the side." 



. _ , The best known and at the same time the typical representative 



Ringed Snake. . . . 



of the group is the common ringed snake (Tropidonotxis natrix), 



inhabiting Europe, Algeria, and West and Central Asia, and attaining a maximum 

 length of 6£ feet. Belonging to a group of the genus in which the number of 

 teeth in the hinder upper jawbone does not exceed thirty, this snake has a single 

 anterior temporal shield on the head, usually seven upper labial shields, of which 

 the third and fourth enter the aperture of the eye, and from one hundred and fifty- 

 seven to one hundred and ninety shields on the lower surface of the body. The 

 eye is of moderate size, and most of the scales are strongly keeled. The colour 

 is usually grey, olive, or brown above, with spots or narrow transverse bands ; the 

 labial shields being white or yellowish, with their dividing lines black; while 

 the uncler-parts are mottled black-and-white or grey. There are, however, several 

 variations as regards the coloration of the neck. In the ordinary variety, for 

 instance, there is a white, yellow, or orange collar, usually divided in the middle, 

 behind which is a broad black collar ; the latter being sometimes alone present. 

 In another variety, mostly from the south of Europe, the collar is altogether 

 wanting, or reduced to a small black patch on each side of the nape ; while in the 



