85 



NOTES ON HELIX PISANA Miiller 

 AND ITS OCCURRENCE AT PORTHCAWL. 



By J. DAVY DEAN, 



Of the Department of Zoology, National Museum of Wales. 



(Read before the Society, May loth, igid 



At the meeting of this Society held November loth, 1915, I exhibited 

 a series of Helix fisana collected in October by Mr. H. M. Hallett 

 and myself at Porthcawl, and we were then under the impression that 

 this was the first genuine record of the species for Glamorgan. Dr. 

 Gwyn Jeffreys' attempt to introduce it at Swansea, and his failure to 

 establish a colony, is well known. There does not seem to be any. 

 further mention of the species for the county until the ^account by 

 the Rev. Dr. A, H. Cooke of finding it in August, 1915, at exactly 

 the same point on the dunes as we did. 



It is extraordinary that two records, made independently, should 

 coincide like this, and yet prove the first for a species with such "care- 

 less" habits, for Helix pisana makes no effort to conceal itself. Dr. 

 Cooke states that it seems obvious that the species has been intro- 

 duced by the agency of man within the last few years. I am inclined 

 to think that the colony is in every way a natural one, and I will give 

 my reasons. 



The most likely source for information in regard to the supposed 

 introduction of the species would be a study of the "past life" of 

 local naturalists. Dr. Gwyn Jeffreys may be acquitted, for he would 

 in all probability have recorded the fact. Mr. F. W. Wotton did not 

 take the species at this locality or there would be some- evidence in 

 his extensive collection at the National Museum of Wales. Mr. 

 Charles Jefferys, of Bath, can give me no information, and I have been 

 unable to find a culprit among other local collectors. So far there 

 is no positive evidence of introduction. 



Dr. Cooke's only reference to the habitat characteristics is his term 

 " herbage." The burrows at Porthcawl, although extending for a 

 distance of two miles, do not offer a suitable habitat throughout for 

 Helix pisana. This suitable flora may be described as the Diplotaxis 

 ietiuifolia association : associated species Senecio jacobcea, Erodinni 

 cicutariuvi, etc. Where this flora begins and ends so also does the 

 H pisana habitat begin and end. There is a margin beyond where 

 it may be taken on the marram grass, but the pure marram grass 

 dunes do not give pisana. Whoever introduced the species was not 



1 Proc. Malac. Soc, vol. xii., p. 4. 



