I40 MARQUAND : MOLLUSCA OF SOUTH DEVON. 



Bulimus acutus van alba Req. and var. elongata. — 



Charleston, near Kingsbridge. 

 B. acutus var. strigata iVEenke. — Also at Charleston. 



B. obscurus Mull. — Ivybridge ; two specimens. 



Pupa umbilicata Drap. — Kennford and Stoke woods, rare; 



more common at Ivybridge and Kingsbridge. 

 Vertigo edentula Drap. — Haldon woods; a single specimen 



only has occurred to me. 

 Balea perversa L. — Mossy walls at Haldon and Matford ; 



rare. Common on tree-trunks in a wood at Kingsbridge. 

 Clausilia rugosa Drap. — Common. Haldon. 



C. rugosa var. tumidula Jeff. — Ivybridge. 



C. rugosa var. gracilior Jeff. — Tamerton FoUiott, near 



Plymouth. 

 Cochlicopa lubrica Mull. — Alphington. Haldon. Matford. 

 Carychium minimum Mull. — Haldon; Common. 



ON HYDROBLE AND ASSIMINE/E FROM THE 

 THAMES VALLEY. 



By J. T. MARSHALL. 



Various correspondents during the last few years have sent me, 

 as Hydrobia si/niiis, a variety of H. veiitrosa which is Jeffreys' 

 var. ovata, and is defined by him as " having a much shorter 

 spire, consisting of only four whorls, which are more swollen 

 than usual, and the last considerably exceeds one-half the shell." 

 I beheve this variety has been considerably distributed among 

 collectors as H. swiilis, and I will therefore point out the chief 

 differences between the two. H. similis is but half the length, 

 much more tumid, thinner and paler, has a pronounced umbilicus 

 and a deep suture, with turreted whorls ; the opercular, however, 

 are almost identical. It occurs in ditches occasionally overliowcd 

 by the Thames, and is strictly local and confined to certain 

 narrow limits, but is not uncommon where found. H. ventrosa 

 var. ovata is the prevalent form on the Plumstead marshes, and 



J.C, vi., Oct., 1889. 



