380 Geographical Distribution of Mollusca. 



I. — Ash Wood Formation. 



(a) Damp Section : deeper soils of the lower wood. 



Clausilia laminata Mont. Associated with : — 



Avion ater L. 

 Vitrea cellaria Miill. 



,, nitidula Drap. 



,, alliaria Miller. 



,, vadiatitla Aid. 



Vitrea crystallina Miill. 

 Euconulus fulvus Miill. 

 Pyramidula rotundata Miill. 

 Helix hortensis Miill. 

 Ena obscura Miill. 



This handsome species with a reputed partiality for the 

 Beech and Ash, is characteristic of the bottom woods of the 

 purer Ash. In such localities it is abundant under the large 

 moss-covered stones or among the fallen branches and twigs. 



Vertigo pusilla Miill. Associated species : — ■ 



Vitrina pellucida Miill. 

 Vitrea alliaria Miller. 

 Euconulus fulvus Miill. 

 Pyramidula rupestris Drap. 

 Hygromia rufescens Penn. 

 Vallonia costata Miill. 



Cochlicopa lubrica Miill. 

 Pupa cylindracea da Costa. 

 Vertigo substriata Jeff (rare). 



,, alpestris Alder. 

 Clausilia laminata Mont. 

 bidentata Strom. 



This species, as evidenced by the association, is marginal 

 to the lower wood, and is found among moss under stones in 

 damp situations, or under top stones of a low crumbling wall, 

 and can be taken in abundance throughout the limestone area. 

 At first sight it would seem that the allied species V. alpestris 

 should take its place here, but though often occurring with 

 V. pusilla on the borders of Ash woods, its real position is in 

 the damp section of the Oak-birch woods, as will be shewn under 

 that heading. V. pusilla, too, is not confined to the north- 

 western counties in the same way that V. alpestris is, occurring 

 frequently in the Midlands, and being even recorded for Devon- 

 shire. 



Hygromia granulata Alder. Associated species : — 



Vitrina pellucida Miill. 

 Vitrea cellaria Miill. 



,, alliaria Miller. 



,, nitidula Drap. 



Hygromia rufescens Penn. 



,, hispida L. 



Helicigona arbustorum L. 

 Helix hortensis Miill. 



This species again is found on the margins of the Ash- 

 woods, more especially just close to a low Ash or Hazel copse. 

 Its abundance places it at once as one of the locally dominant 

 species. It occurs in large colonies in the patches of Poientilla 

 anserina, etc. 



Sub-section — Beech Woods. 



The noticeable feature of the Beech-woods is the fondness 

 for them of the hispid shells — those which have a more than 



Naturalist' 



