DISTRIBUTION 123 



longissitnus. The others may be described as southern 

 forms, two only as ranging from west to east: 

 Zamenis gemonensis and Ccelopeltis monspessulana ; 

 one of more central habitat: Vipera ursinii. The 

 remainder may be divided into two groups — those of 

 more western, and those of more eastern distribution. 

 To the first group belong Tropidonotus viperinus, 

 Zamenis hippocrepis, Coluber scalaris, Coronella giron- 

 dica, Macroprotodon cuctdlatus, Vipera aspis and Vipera 

 latastii ; to the second, Typhlops vermicidaris f Eryx 

 jaculus, Tropidonotus tessellatus, Zamenis dahlii, Colu- 

 ber quatuorlineatus, dione, leopardinus, Contia modesta, 

 Tarbophis fallax and iberus, Vipera renardi, ammodytes, 

 lebetina, and Ancistrodon halys. 



A remarkable fact in the distribution of Euro- 

 pean Snakes is the altitudinal range of Vipera berus, 

 V. aspis, and V. ursinii. The first being the northern- 

 most snake, generally distributed in Northern 

 Europe and more locally in the south, should, one 

 would expect, be a mountain form in the south. 

 This is so in Switzerland, where it occurs chiefly 

 between 2,500 and 9,000 feet, on the northern aspect 

 of the Alps, whilst V. aspis lives at altitudes below 

 5,000 feet ; but on the southern aspect of the same 

 chain things are reversed, and V. berus is replaced 

 by V. aspis, which reaches an altitude of 9,700 feet, 

 whilst the former shows a tendency to abandon the 

 mountains, and has established ifself in a few locali- 

 ties in the plain of North Italy. Again, in France 



