8$ THE ZOOLOGIST. 



the continental Vipera aspis to the rank of a mere subspecies of 

 V. berus. Although the facts of the case are correctly stated by 

 the distinguished Italian zoologist, I do not think herpetologists 

 are at all likely to agree with his conclusions ; the more so as I 

 fear a similar treatment would necessarily apply to many other 

 largely distributed species when we once undertake to test the 

 constancy of technical characters on a very great number of 

 specimens from various parts of their habitat. No single 

 distinctive character, in the case of allied species, appears to be 

 absolutely constant ; combinations of characters seem to be all 

 we have to fall back upon in such cases. That Vipera aspis 

 should still be maintained as a distinct species I have no doubt. 

 The large material which I have brought together, and which I 

 am endeavouring to increase, justifies this assumption ; for 

 although no one of the three cardinal characters used for the 

 discrimination of that species from V. berus is in itself constant, 

 I have not yet come across a single specimen which I could not 

 satisfy myself to belong, without doubt, to the one or to the 

 other. What we are most in want of at present are accurate 

 statistics showing the range of variation assumed by the species 

 in any limited area. And I hope, by specifying the points which 

 require investigation, to enlist the interest of those residing in 

 districts where the Adder is abundant, — at the same time, by 

 stating the results of my observations up to the* present time, 

 to satisfactorily answer some of the questions which have at 

 various times been raised in the correspondence of this Journal. 



1. Habitat. — Vipera berus inhabits the whole of Northern 

 Europe and Northern Asia, from Great Britain to the Island of 

 Sachalin. In Scandinavia it reaches to 67°, in Western Siberia 

 to 64°, in Eastern Siberia to 54°. It is found in France (as far 

 south as 46° in the west, and also on the Central Plateau), in 

 Belgium, Holland, Germany, Switzerland, Austria-Hungary, 

 Bosnia, Italy as far south as the Gran Sasso. It is extremely 

 scarce in the Jura, but common in the Alps, between 2500 and 

 9000 feet. Absent from the South of France and the Pyrenees, 

 it reappears in the North-west of Spain (Asturias and Galicia). 

 Eastwards it extends to Roumania, Southern Russia and Crimea, 

 the Caucasus, the Kirghiz Steppes, and Turkestan. 



The Viper, which is absent from Ireland and the Shetlands 

 >m<l Orkneys, occurs from the extreme North of Scotland to the 



