HORSLEY : HELIX NEMORALIS AND HELIX HORTENSIS. 21 



nemovalis, on a calcareous soil. And in a district where both are 

 found nemovalis will affect the parts where the chalk or limestone 

 comes to the surface, and hortensis will be in the hedges of the 

 valley where alluvial soil to some extent covers the calcareous 

 rock. Have conchologists noticed, by-the-bye, that in many 

 places both these shells are common in wayside hedges and on 

 the sides of high roads, but far less common in hedges a field or 

 so distant from the road ? One might have thought that the less 

 amount of cover and the greater amount of enemies to be found 

 close to the roads in comparison with field hedges would have 

 reversed the position of affairs. But it seems to me that the 

 dust of the high road provides lime so conveniently comminuted 

 for the building up of their shells that they have been drawn, so 

 to speak, into public life by its advantages. 



Both shells being in their typical form five-banded, one may 

 notice that the bandless or unicolourous varieties are much more 

 common in hortensis than in nemoralis, one observer finding that 

 52-52 of the hortensis and only i7'86 of the nemovalis he collected 

 in one district in Middlesex were of the bandless kind. This one 

 might expect from the fact that hortensis is, on the whole, feebler 

 than its cousin, and so more likely to be without pigment-pro- 

 ducing powers, and this is borne out by the rarity of the 

 translucent -banded forms in nemoralis and their comparative 

 frequency in hovtensis ; and also by the variety with only a 

 peripheral band being quite common in nemoralis, but distinctly 

 rare in hortensis. But one must note per contra, and contrary to 

 one's expectation, that the variety (sometimes called coalita) in 

 which from excess of pigment power all the bands are united 

 into one broad belt of chocolate colour that occupies nearly the 

 whole whorl, is much more common in the weaker hortensis than 

 in the sturdy nemoralis. 



Other differences are these : The albino form is not un- 

 common in hortensis, though one may notice that the dead white 

 appearance of the shell gives way to a white tinged with yellow 

 when the animal is extracted ; but in nemoralis there is hardly a 

 really albino form, the name var. pallida being more justified 

 than that of var. albiiia. The variety lilaciua, again — a tint, by- 

 the-bye, very rare in other Helicidae — is doubtfully found in 

 nemoralis, though abundant in certain localities for hortensis. Nor 

 are the two species at all alike as to unicolourous specimens of a 

 brown colour. In nemoralis we have the vars. castanea and olivacea. 



