290 HAAS: ABIDA AND CHONDRINA. 



arrangement, which seems to me unnatural, was in the first 

 place that the forms in question are all more or less deficient 

 in teeth or lack them altogether, while typical avenacea occurs 

 in the Pyrenees but seldom. Further, that the forms erected 

 as distinct species and varieties are in large part known only 

 by descriptions, being scarcely to be found in collections, 

 which naturally made a correct estimate of them impossible. 



I hope to be able to demonstrate by my arrangement that 

 the characters which have appeared certain marks of distinc- 

 tion to the authors of the many Pyrenean species and varieties 

 of Chondrina, such as shape and size of the shell, number of 

 whorls, strong or superficial striation, structure of the peri- 

 stome, and not least, the number and combination of apertural 

 teeth and folds, can be shown to lead into one another, even 

 among specimens taken in the same place, and therefore can 

 not be used for specific and varietal distinction. 



The forms placed together by Pilsbry (I. c.) belong, accord- 

 ing to my researches, to two different local races. The first, 

 which must take the name farinesi, is restricted to the High 

 and East Pyrenees, as well as in Aragon, about to the Ebro, 

 and northern Catalonia as far as the latitude of Barcelona. 

 The second, which groups around P. jumillensis Pfr., belongs 

 to the eastern half of southern Spain, and comes into contact 

 with the preceding race in the north. How the Chondrinas 

 from Asturia and the Basque provinces which muster about 

 P. kobelti Hid. are related to the first two local races I cannot 

 certainly ascertain without collecting experience and more 

 ample material than is now at my disposal. The similarity of 

 this group to more fully toothed forms of the Pyrenean fari- 

 nesi is great, but the two do not seem to me to be identical. 



In Pilsbry 's list of Pyrenean Chondrinas of the group of 

 bigorriensis there is a series of forms which I must refer to 

 the avenacea group, and which belong in three form-series I 

 have defined. 



10a. Chondrina avenacea farinesi (Des M.). PI. 27, figs. 

 1 to 5. 

 Synopsis of the combinations of apertural teeth of Chon- 



