IO(> 



THE LAND AND FRESHWATER MOLLUSCA 



OF CHESHIRE. 



CHARLES OLDHAM, 

 Rom Hey, Cheshire. 



The greater part of the county of Chester is an extensive and 

 nearly level plain, which lies between the Mersey and the Dee. 



Near Audlem, on the south-eastern border, there is a small 

 patch of the Lower Lias, but, with that exception, the whole plain 

 rests upon the New Red Sandstone, which is frequently covered 

 to a considerable depth by glacial clays, sands, and gravels. East of 

 the great fault, which coincides roughly with a line drawn from 

 Stockport through Congleton to a point on the Shropshire border 

 near Alsa°;er, the ground rises abruptly, and attains an altitude of 

 from 1,800 to 1,900 feet in several places. Except in the doughs 

 and river valleys, this hill country is bare and treeless, the Permian 

 Rocks of which it is composed being even less suited to the needs 

 of land shells than is the Trias of the plain. 



Although a considerable proportion of the British terrestrial 

 species have been recorded from Cheshire, the number of individuals 

 inhabiting any one spot is far smaller than in chalk or limestone 

 districts, and, as might be expected from the absence of these 

 formations, Helix lapicida, Pupa secale, Caalieides acicula and 

 Cyclostoma elegans have never been taken in the county. Such 

 thick-shelled species as Helix aspersa, nemoralis } hortensis and 

 arbustonim are comparatively rare; and the scarcity of Helix 

 rufescens is remarkable. In places where the river valleys are well 

 wooded, as at Marple and Romiley on the upper Mersey, and 

 Ashley on the Bollin, some of the smaller Helices and various 



Hy 



Hyalinia 



shell on limestone, so far as my experience goes, is in many places 

 abundant. In Wirral, the hammer-headed peninsula between the 

 Dee and Mersey estuaries, 



H. 



muscorum are found on the coast, but H. virgata, if it occurs at all, 

 is very rare. With the exception of Gtomalacus macuhsus and two 

 species of Tes/ace/Ia, all the slugs have been taken in Cheshire; 

 though the distribution of several of the species is little known, and 

 the neglect of these interesting creatures by local mycologists is 



greatly to be deplored. 



If the land shells are comparatively scarce, the reverse obtains 



with the freshwater species. It is true that the 



streams 



April 1896. 



