EUEOPEAN" KEPTILE-FAUNA. 67 



with the warmer regions of the earth's surface, which appear to be 

 more suitable to the habits of this class of animals. In the whole 

 of Europe north of the Alps, or in what has been recognised as 

 the "European province," naturalists recognise only about fifteen 

 species of snakes, and a nearly equal number of lizards ; in the 

 Nearctic division, while the number of lizards is not very much 

 greater — about twenty species — that of serpents is very materially 

 increased — to about eighty to ninety species — most of them belong- 

 ing to the family of colubers, which includes the black constrictors. 

 The headquarters of the rattlesnakes are situated in the debatable 

 land bordering the Neotropical realm. 



The entire reptile-fauna of Europe is, according to Schreiber 

 (" Herpetologia Europaea," 1875), comprised in sixty-two species, 

 of which twenty-five are serpents, thirty-two saurians, and five che- 

 lonians. Northern Europe, or the region lying to the north of the 

 fifty-fifth parallel of latitude, is represented by but six species: 

 Viperus (Pelias) berus, Tropidonotus natrix, Coronella Austriaca, 

 Anguis fragilis, Lacerta vivipara, and L. agilis ; the chelonians are 

 completely wanting in this tract. Central Europe, including the 

 Alpine system of mountains, has twenty-nine species, while the en- 

 tire number is represented in the Mediterranean fauna. A number 

 of additional species has been added to the list enumerated by 

 Schreiber ; but these do not materially affect the ratio for the dif- 

 ferent zones. The most northerly of all serpents appears to be the 

 common European viper, Viperus (Pelias) berus, whose range in 

 Scandinavia extends to about the sixty-seventh parallel of latitude. 

 The species is distributed throughout nearly the whole of Europe, 

 and eastward through Central Asia to the Japanese islands; it is 

 also found in England and Scotland, and in some of the Scotch 

 islands (Arran, Hebrides). Tropidonotus natrix (Natrix vulgaris), 

 a species of equally broad distribution, which is stated to ascend 

 mountains to a height of six thousand feet, is found in Norway as 

 far north as the sixty-fifth parallel. 



The most northerly, and at the same time most broadly distrib- 

 uted, species of European lizard is the Lacerta vivipara, whose range 

 in Norway is extended by Collett to the seventieth parallel of lati- 

 tude. It is found throughout most of Europe (wanting in the Ibe- 

 rian Peninsula, Southern Italy, and Greece), and is an inhabitant of 

 the Alpine region, up to an elevation of nine thousand feet. 



