Geographical Distribution of Mollusca. 



319 



On the Millstone Grit in conjunction with Tanacetum 

 vulgar e we find H. caper ata associated with : — • 



Agriolimax agrestis L. Helix aspersa Miill. 

 Avion ater L. hortensis Miill. 



Hvgromia hispida L. Ena obscuva Miill. 

 rufescens Pennant. 



As these associations occur near the sea, probably the 

 characteristic species is H. itala — with H. caperata in Lonsdale 

 as the dominant. For elsewhere one often finds on the dry 

 pastures near the coast, H. itala in abundance, associated with 

 H. virgata, H. caperata and H. cantiana 



H. caperata exists in Lonsdale in colonies on the drier sea- 

 ward pastures, and on the windward (here the western side) 

 of calcareous pastures further inland. It is the only species 

 of the Helicella group which can be considered as well estab- 

 lished in this district. H. virgata, so abundant elsewhere, is 

 entirely absent. H. itala seems confined to just a few places, 

 and can rarely be taken in any numbers. 



Vallonia excentrica Sterki. 



Vertigo pygmcea Drap. (Example — Far Arnside). 



These two species will be found in dry weather under loose 

 stones lying in the open pastures at a low level — often in a dry 

 exposed situation. While either species may also be found in 

 the Wet-Grassland or Woodland sections, the above is a charac- 

 teristic feature in their distribution. 



Pupa secale Drap. (Example — Witherslack). 



Separating the low-level seaward pastures from the higher 

 wind-swept pavements or grazing lands, there are in some places 

 vertical rock faces often of a considerable height. On several 

 of these occurs Pupa secale associated with Pyramidula rupestris 

 (as the dominant) and Pupa cylindracea da Costa. It is 

 really a southern type, abounding on the calcareous formation 

 and the most northerly station so far recorded is Scout Scar, 

 Kendal. Like P. rupestris it seems to need very little moisture. 

 Similarly the southern Pomatias elegans finds in the district 

 its most northerly extension, which is paralleled by the dis- 

 tribution of Asperula cynanchica and Clematis Vitalha. 



Sub-section — Subterranean.. 



Caecilioides acicula Miiller. (Example — Silverdale). 

 An isolated species * — 

 [To be continued). 



* Possible association is with Viirea crysiallina Miiller, a species almost 

 subterranean in its habits, and common in the district. 



igog Sep. i 



