SEKPENTS. 331 



in the tropical regions of the earth's surface, and rapidly diminish- 

 ing toward either pole. Excepting, however, members of the 

 family of water-snakes (Hydrophidaa), which are especially abun- 

 dant in the Australian and Indian seas — ranging westward to Mada- 

 gascar, and eastward to Panama — the order is only exceptionally 

 represented in the strictly oceanic islands, in this respect dififering 

 from the lizards and agreeing with the amphibians. Evidently, 

 the animals of this class, like the Amphibia, possess no facilities 

 for traversing broad arms of the sea. 



With our deficient knowledge of many of the more favoured 

 regions of the globe it is impossible to arrive at any estimate of 

 the numerical extent of the order, but it may be safely assumed 

 that there are considerably more than one thousand clearly defined 

 species known to naturalists, of which very nearly one-half are 

 found in British and Farther India, and the East Indian Archi- 

 pelago. Mr. Blanford places the number of species from British 

 India and its dependencies alone at two hundred and seventy-four.* 

 In Europe, north (and inclusive) of the Alps, there are some fifteen 

 or more species, of which three, the common viper or adder (Vipera 

 [Pelias] berus), the grass or ringed snake (Tropidonotus natrix), 

 and the Coronella Austriaca (leevis), penetrate beyond the fifty-fifth 

 parallel of latitude. These are the only species found in Scandi- 

 navia, the British Isles, Denmark, Holland, and Belgium. The 

 most northerly of all serpents is the common viper, whose range 

 embraces the whole of Europe and Northern Asia, and which in 

 Scandinavia extends to the Arctic circle; in the Alps it is occa- 

 sionally met with at an altitude of nine thousand feet. The north- 

 ern limit of the ringed snake appears to be the sixty-fifth parallel. 

 Germany has in all six or seven species,"" the three above men- 

 tioned, and Tropidonotus tessellatus, Elaphis flavescens (jEsculapii), 

 Zamenis viridiflavus (doubtful), and Vipera aspis (the asp), the last 

 very largely distributed throughout the whole of France and Switz- 

 erland, and the commonest of the venomous serpents of Italy. It 

 does not appear to ascend the Alps to elevations much exceeding ' 



* The census of the other Eeptilia is as follows : Chclonia fifty-four, Cro- 

 codilia four, Laoertilia one hundred and eighty-two. The Amphibia com- 

 prise about one hundred species, of which one only belongs to the tailed 

 division, and five to the Pseudophidia (Coecilia). " Journ. Aslatio Soe. 

 Bengal," Dec, 1881. 

 15 



