ii8 HELICID^. 



fragments may frequently be seen. Considerable 

 difference of opinion prevails among conchologists 

 as to whether the forms hortensis and hybrida should 

 be regarded as distinct species, or as varieties only. 

 Gwyn Jeffreys believes them to be " merely local or 

 casual varieties " of the typical form nemoralis, and 

 states (as one of the reasons which lead him to this 

 conclusion) that he has "never found any two of 

 these forms living together," B.C.^ vol. i. p. i88. In 

 his supplement, however, he somewhat modifies this 

 assertion, remarking that he has since found nemoralis 

 and horte7isis " living together, but passing one into 

 the other." That these forms very frequently asso- 

 ciate together is a fact well known to most concho- 

 logists ; but whether the characters which distinguish 

 them from one another are specific or merely varietal 

 is another question. It was stated in the preface to 

 this volume that I proposed to follow the accom- 

 plished author of 'British Conchology' in the method 

 of arrangement, as well as in the nomenclature which 

 he has adopted, and as I am anxious to avoid the 

 confusion which any deviation from that intention 

 might produce, I have described and figured hortensis 

 and hybrida as varieties of nemoralis, though I 

 strongly incline to the belief that hortensis at least is 

 a distinct species. The following remarks embody 

 the chief reasons which lead me to this conclusion. 

 The greater part of the spring and summer of last 

 year (1878) was spent by me in Normandy, where 

 H. nemoralis^ hortensis, and aspersa, as well as many 

 other species, occur in endless profusion. An un- 

 usually favourable opportunity was thus afforded me 



