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HELIX NEMORALIS AND H. HORTENSIS : THEIR COLOUR 

 AND BAND VARIATIONS AND DISTRIBUTION- 

 SOME COMPARISONS. 



By W. GVNGELL. 



(Read before the Society, Feliruarj' nth, 191 1). 



The enormous number of recorded observations of these two closely 

 allied species of British mollusca must cause anyone to hesitate before 

 venturing to make any further contribution to the literature of the 

 subject. As, however, the writer has had exceptional opportunities 

 for observing these two Helices in a large number of localities, he 

 hopes that the following notes may be of some interest. 



Both species have been sought by the writer in hundreds of dis- 

 tricts, scattered over twenty English counties, and in nearly all these 

 counties both species have been found, from Cumberland and Dur- 

 ham in the north, through the Midland and Welsh border counties, 

 to Somerset in the south-west, and to Norfolk in the south-east ; the 

 main result being that Helix 7tetiioraIis has been found in almost 

 twice as many districts as the smaller species, the comparative 

 abundance being as 52 is to 27. It thus appears that if anyone, 

 dropped from the skies at random, anywhere in England, were to 

 search at once for both species, his chances of finding Helix 

 nemoralis would be double that of his turning up Helix hortensis. 



But the distribution of the two species is by no means the same 

 in northern and southern England, the larger mollusk prevailing in 

 most southern districts, and the smaller one being much the more 

 abundantly found in the north, excepting in the neighbourhood of 

 the sea-shore. Here Helix iief/iofalis always reigns supreme. It has 

 been found by the writer on almost every part of the coast that he 

 has visited. Precipitous sea-cliffs, grassy slopes, and bare sand-hills 

 seem to be equally favoured by this species, whilst Helix hortetisis 

 has been found to be almost invariably absent from such situations, 

 though very frequently occurring in the road-side hedgebanks half- 

 a-mile inland. The different haunts favoured by the two species are 

 very noticeable on the Yorkshire coast. Here the larger one has a 

 continuous range along the coast on cliffs of Calcareous Grit, Boulder 

 Clay, and Chalk, or low-lying sand-hills washed by the spring tides, 

 the species ranging down as low as grass or any herbage will grow. 

 These exposed situations, however, are not favoured by Helix hor- 

 tensis, though very exceptionally odd colonies may be found, as for 

 example, on one side of the Castle Hill, Scarborough. But as this 

 particular spot was formerly a "pleasure garden," the species is very 

 likely to have been introduced. If, however, we leave the sea-cliffs 

 and turn into any of the high-roads, we shall find the smaller species 



