278 HAAS: ABIDA AND CHONDRINA. 



of A. affinis (Rossm.), but by the structure of the aperture it 

 does not belong to this, but to pyrencearia. 



Pupa nansoutyi Fag. and P. occidentalis Fag. in Wester- 

 lund are not known to me, but it appears certain, from their 

 descriptions, that they also are to be referred to A. pyren- 

 (varia. 



Abida pyrencearia is a truly Pyrenean snail, not straying 

 beyond the limits of the mountains. On the Spanish side it 

 is known to me only from the highest parts; I never found it 

 below an elevation of 1400 m. In all its localities it is very 

 abundant, upon cliffs and under stones. 



The group of Abida affinis (Rossm.). 



While all Pyrenean Abidas already discussed prove to be 

 indeed very variable, so as to give occasion for the proposi- 

 tion of many new names, none of these variation-forms proved 

 to be characteristic of definite, well-defined regions, so that 

 none of the new "species" or "varieties" could be retained 

 as local forms (subspecies). It is otherwise with A. affinis, 

 which in the area it inhabits has developed into a series of 

 well-marked forms, which in their respective districts do not 

 intergrade with the others. By the admission of the occur- 

 rence of such local races it must not be understood that this 

 species and its subspecies are less variable individually than 

 the Abidas already discussed. In all localities whence I have 

 abundant material — and they are many — it is seen that the 

 shells ocillate between strictly cylindric and distinctly fusi- 

 form; and in the latter case the point of greatest diameter 

 may be removed a varying distance from the middle of the 

 shell. With relatively constant length, the diameter is sub- 

 ject to great variation; shells of 11 mm. long may have a 

 diameter of from 2 to 3.5 mm., in fusiform as well as in 

 cylindric shell-forms. 



Up to this time, four local races of A. affinis are known to 

 me, of which two do not live in the Pyrenees, but in the ad- 

 joining mountainous regions southward. 



