20 horsley: helix nemoralis and helix hortensis. 



conchologists, are distinct species, although M. Souverbie, 

 Curator of the Bordeaux IMuseum, waxed very vehement when 

 discussing the matter witli me, and maintained they were only 

 varieties. 



Others, in earlier days, maintained that the two species 

 were so allied that there was a hybrid form, which form 

 we should now call simply H. hortensis var. fuscolahiata. I have 

 never seen nemoralis and hortensis pairing, although I have care- 

 fully looked out for instances, nor have I met any one who has. 

 This is a strong argument for their diversity, although an occa- 

 sional pairing would not prove them to be the same species. 



The second difference is an anatomical one, the obvious and 

 unvarying difference between the darts of the two species. That 

 of nemoralis is straight and very like the Roman short sword ; that 

 of hortensis is curved. The length of the dart in nemoralis is 

 7-8 mm. ; that of hortensis only 4 mm. The observation of the 

 dart is of especial value when a form is found with white 

 peristome and transparent bands associated with undoubted 

 nemoralis. Is it a stray arenicola ? or is it the much rarer hyalo- 

 zonata form of nemoralis ? The shells tell you little ; the darts 

 leave you no doubt. In fact, as nemoralis var. alholahiata is so 

 rare in most places, it is always well to verify it by an examina- 

 tion of the dart. 



The size of the two shells varies — nemoralis is usually 

 i6\ millimetres in height and 22^ in breadth, and hortensis 

 16 mm. in height and 18 mm. in breadth, and generally 

 the former is more variable in size than the latter. My largest 

 nemoralis is 32 mm. in breadth, and my smallest hortensis 11 mm. 

 The difference I have especially noticed abroad, where nemoralis 

 is often much larger than the average size in England, but 

 hortensis remains the same. A third point to be noticed is that 

 it is not usual, though by no means unknown, for the two species 

 to be found in the same habitat. I can only say, in mentally 

 reviewing the very many localities in which I have noticed or 

 gathered thousands of these shells, that I can recollect a hedge 

 here and a bank there where both were found mixed and in 

 fairly equal proportions. Even where both are found in the 

 same lane, one may be exclusively found at one end and the 

 other at the other. It seems to me, also, that nemoralis is more 

 dependent than its cousin, or hortensis less dependent than 



