266 THE ZOOLOGIST. 



ON THE OCCUKRENCE OF VIPERA BERUS IN 

 THE PYRENEES, NEAR SAN SEBASTIAN. 



By Edward Britten. 



For a long time considerable interest has been taken in the 

 Vipers of the Pyrenees, owing to their resemblance both to 

 V. berus and V. aspis, the former more properly belonging to 

 the North of France, the latter to the South. According to a 

 great authority (F. Latasti), the Vipers of the French Pyrenees 

 are all referable to V. aspis. In North-west Spain, however, 

 V. berus reappears to the exclusion of V. aspis. The Spanish 

 V. berus has been regarded as constituting a distinct subspecies 

 (V. berus seoanei), on characters which Mr. Boulenger has shown 

 to be inconstant (cf. ' Zoologist,' 1885, p. 373). 



The writer has recently taken a specimen from the south- 

 west of the range which presents such a combination of the 

 characteristics of V. berus, V. seoanei, and V. aspis as to make it 

 at first somewhat difficult to classify, and to render its principal 

 features worth recording. Mr. Boulenger gives it as his opinion 

 that the snake should be regarded as a V. berus. 



It is a female measuring 475 mm. It resembles V. berus 

 in general colour and markings, which are somewhat lighter 

 than in most females. Each belly-plate is bordered by a clear 

 white line. The end of the snout is distinctly turned up, though 

 not to the same degree as in a typical V. aspis. The supra- 

 ocular shields are less prominent than in V. aspis, and more 

 than in V. berus ; two complete rows of scales between eye 

 and labial shields on the right side and two incomplete such 

 rows on the left. Ventral plates 143, subcaudals 32 pairs. 



In addition to the foregoing data it is significant that a small 

 specimen 200 mm. long, with 138 ventral plates and 29 sub- 

 caudals, was obtained in the same locality, and agrees in every 

 respect with a typical young V. berus. Incidentally the fact is 

 thereby established that V. berus occurs on the Spanish side of 

 the Pyrenees. It would be interesting to examine a number of 

 Vipers taken from the hills between Pau and San Sebastian, in 

 order to decide on the range of variation of the Vipers in the Pyre- 

 nees, and on the alterations which such aberrant specimens as the 

 one here noticed will necessitate in the definition of the species. 



