354 



ON THE GEOGRAPHICAL DISTRIBUTION OF 

 MOLLUSCA IN SOUTH LONSDALE. 



Rev. C. E. Y. KENDALL, B.A., J. DAVY DEAN, and 

 W. MUNN RANKIN, 'Sl.Sc, B.Sc. 



[Contiimed from page jig). 



At present it is impossible to determine the exact distribu- 

 tion of this shell. Evidence that it is locally abundant may be 

 seen from examination of various limestone ' pavements ' at 

 Silverdale and Hampsfell (Grange). After heavy rains numbers 

 of dead specimens are washed down from the loose sub-soil 

 above, and mdcy be found in the crevices and on the ledges of 

 the rock below the ' pavements.' 



2. Coniston Limestone. 



Pupa cylindvacea da Costa. Associated species : — 



Agrioliniax agrcstis L. I Cochlicopa lubrica Miiller. 



Pyramidula rotuudata Miiller. | 



The principal feature connecting this formation with those 



of the Carboniferous Limestone is the abundant presence of 



this species. It takes the dominant position on the Coniston 



Limestone, and is abundant in exposed situations within the 



1000 feet zone. The absence of Pyramidula rupestris is 



noteworthy, and the habitual occurrence of P. rotundata is 



important. The association is a non-calcareous one. Lt is 



noteworthy that in all its extension across the Lake District 



no distinctively calcareous plant species, with the possible 



exception of a few lichens and mosses, may be found on this 



rock. In Ribblesdale, however, it is somewhat more productive 



showing a much closer affinity to the Carboniferous Limestone. 



Nox-Calcareous Pastures. 



Heaths (Calluna and Grass Heaths). Associations shewing 

 conditions uncongenial to ordinary plant life. 



Limax arborum Bouchard-Chanteraux. Associated species : 



Agviolimax agvestis L. 1 Pyramidula rotundata INIuller. 



Vitrea alliaria Miller. | 



On the heaths this species would appear to be the dominant 

 one, for though ' the Tree Slug,' it is by no means confined to 

 trees. It occurs in the open at Ambleside, and on the higher 

 parts of Coniston Old Man, reaching an altitude of 2600 feet. 



Naturalist, 



