378 



ON THE GEOGRAPHICAL DISTRIBUTION OF 

 MOLLUSCA IN SOUTH LONSDALE. 



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

 W. MUNN RANKIN, M.Sc, B.Sc. 



{Continued from page jjg). 



Neritina is a true non-calcareous species, while Ancylus 

 occurs in both calcareous and non-calcareous rivers, and can 

 exist in shallower and swifter streams than the former. L. 

 aiiviciilaria is rare, and is of a small acute form. Unio mar- 

 garitifer is local, but abundant in the deeper pools of the lower 

 river. This interesting species is characteristic of a northern 

 fauna, its range extending from the Conway and Dee throughout 

 the north-western counties into Scotland, right into the High- 

 lands. It is a favourite food of the otter, and seems to abound 

 in rivers where this animal is common. 



(c) The Smaller Rivers (Example— R. Bela.) 



Marsh. 



Open Water. I Reed Belt. 



L. pereger Miill. Planorbis carinatiis Miill 



Neritina fliiviatilis L. I Bithynia tentaculata L. 



This is a much slower moving river than the Lune, and shews 

 interesting features. In the reaches examined Ancylus was 

 absent. LimncBa pereger and Planorbis carinatus seem plentiful. 

 The latter is a southern and eastern type, and is only local in 

 the north-western counties. This is the only locality for it in 

 Lonsdale. 



Note. — We have no records for the marsh section of these 

 non-calcareous streams. Captain Farrar gives the following 

 for the margins of the becks of the Lake District, which note is 

 of interest, and may apply to the examples already taken. 

 Open Water. 



L. pereger MuU. 

 Ancylus fluviatilis Miill. 



Marsh. 



Agriolimax Icsvis Mull. 

 Hygromia fusca Mont. 

 Pupa anglica Fer. 



He states that H. jusca occurs ' wherever sedges border the 

 swiftly-running becks.' Pupa anglica is a moss feeder, and 

 though occurring often in woods, this may be its true position. 



5. Heath Moors. 



§ I.— -Lowland : Ditches and pools on the mosses. 



Open Water. 

 Limit cB a pereger Miill. 



Reed Belt. 



Limnesa palustris 



Mull. 



Marsh. 



Planorbis spirnrbis L. 

 Pisidium obtusalc Pf. \ 

 Ra.Te]yAplecta hypnorum. 



Naturalist, 



