2562 SCALED REPTILES 



out at sea. It produces living young, and subsists on fish. A third Oriental genus, 

 likewise known merely by one species (Xenodermus jai'anicus) , has large shields on 

 the under surface. In the other two genera Stolic~kaia from India, and Nothop- 

 sis from Central America not only are there lower shields, but the granules on 

 the head are replaced by large shields. 



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

 " s largest subfamily of the solid-toothed colubrines, which is known as 

 the Colubrina, 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 characterized 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 jawbone varying in number from eighteen to forty, 

 and forming a continuous series. 



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

 itan 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. Giinther writes that the typical wa- 

 ter snakes " are easily recognized by their stout, 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 neighborhood 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 ex- 

 cellent 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 fresh-water snakes, but on the side." 



The best-known and at the same time the typical representative of 

 e the group is the common ringed snake ( Tropidonotus natrix], inhabit- 

 ing Europe, Algeria, and West and Central Asia, and attaining a maximum length 

 of six and one-half 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 bod}'. The 

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

 usually gray, olive, or brown above, with spots or narrow transverse bands; the labial 

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



