42 REPTILES 



America displayed by its tortoises, or indeed to Madagascar. 

 This latter island, on the other hand, lacks stellions, monitors, 

 typical lizards, slow-worms, and amphisbasnas, while it possesses, 

 in addition to the cosmopolitan skinks and geckos (of which 

 latter there are some very peculiar types) chamaeleons and the 

 African families Zo7i7iridcE and Gerrhosanridce. 



Lizards have the most northerly range of all reptiles, ex- 

 tending in British Columbia to about latitude 56 and in the 

 Old World almost to the Arctic circle. In the southern hemi- 

 sphere they extend to the extremity of the American con- 

 tinent. 



Snakes, on the other hand, stop considerably short of the 

 above limits, both in the north and in the south. The sub- 

 order is practically cosmopolitan, New Zealand being the only 

 large island (other than those of the polar regions) in which 

 it is wanting. Nor is this all, for dangerously poisonous 

 species are to be met with throughout the distributional area of 

 the group with the exception of Madagascar, 1 which enjoys 

 complete freedom from such noxious creatures. A great contrast 

 in this respect is presented by the Oriental region of geographical 

 zoology (India, the Malay countries, and southern China), which 

 is the home of members of the three most important groups of 

 poisonous serpents, and has consequently the highest death-rate 

 from snake-bite of any part of the world. 



The four families of burrowing snakes, namely Typhlopidce, 

 G/aucom'idcz, Ilysiidce, and Uropeltidce, appear to indicate an 

 ancient type, since some of them retain traces of the hind limbs, 

 and it is therefore not surprising to find that, as a whole, they 

 have a wide geographical range, although the last of the four 

 is restricted to Southern India and Ceylon. The boas and 

 pythons (Pytlionidce), again, which likewise appear to be a com- 

 paratively ancient group, have also a wide range in space, being 

 almost cosmopolitan. Of the two subfamilies into which the 

 group is divided, the pythons {Pytkonince) are almost exclu- 

 sively Old World types, large species of the typical genus occur- 

 ring in Africa, India, the Malay countries, etc., and smaller forms 

 in Australia. The one exception to the Old World distribution 

 of this subfamily is the occurrence of Loxocemas bicolor (the 



1 Ireland has, of course, the same immunity, but it can scarcely be recog- 

 nised as a large island. 



