3l6 JOURNAL OF CONCHOLOGY, VOL. l6, NO. ID, 0CT0BK:R, I922. 



while H. nemoralis is found in both areas although it is not so 

 frequent in the damp as in the dry area. H. nemoralis does not 

 appear to prefer any particular part of the valley side, but is found 

 equally distributed over the whole length. 



On either side of this habitat H. nemoralis is found, but here it 

 appears to occur only in the neighbourhood of the out-cropping 

 limestone which now appears in much larger masses ; H. hortensis is 

 no longer found. 



In this colony six varieties of H. nemoralis are found, tlie per- 

 centage frequency — calculated from five thousand (5,000) shells that 

 have been collected — being: — rubella 00300 i'3, nibella 00000 6*9, 

 castanea 00000 11, libelhila 00000, albolabiata 5"i, libellula oot^oo 3*4, 

 and libelhila 00000 72-3. One or two shells of the variety castanea 

 00000, albolabiata and rubella 00000, albolabiata were also found ; the 

 frequency with which shells possessing more than one band occur is 

 one per thousand. Here we have an entirely different distribution 

 from that at Millers Dale, where the majority (91 %) of the H. nemoralis 

 were libel lula 00300 ; however, in both colonies the percentage of 

 rubella 00300 is very small. From a study of the shells collected 

 several very interesting points were noticed : — {a) there was a tendency 

 towards pink and paler lips in the variety castanea, this tendency 

 apparently not being present in the variety rubella ; (b) the occasional 

 development of teeth in the mouth, one or two teeth being sometimes 

 found just inside the peristome, near the suture ; (<:) the tendency for 

 the lip to become thickened, with formation of a small but definite 

 umbilicus ; (d) that white lips were only present, in any number, in 

 the variety libellula 00000. In the case of H. hortensis only the type 

 was found although both the ground colour and the banding varies. 



Once again we find H. arbustoruni present, but it is confined to the 

 damper area and the nettles in the river bed. On the limestone face 

 at the top of the hill H. lapicida is found. 

 Thorpe Cloud. 



In the hedgerows on either side of the road from Thorpe Cloud to 

 Ashbourne a colony of H. hortensis and H. nemoralis has established 

 itself. At the bottom of the hedge-banks is a grass-grown ditch and 

 practically the whole length of the habitat is shaded by overhanging 

 trees ; here we have a typical roadside flora. In this instance we find 

 that the two species of molluscs live together side by side and exhibit 

 little or no tendency to separate into two colonies and in this habitat 

 they can be said to be truly associated. 



In the case of H. hortensis only shells with yellow ground colour 

 are to be found, but in the case of H. nemoralis the varieties libellula, 

 castanea and rubella were seen. 



