286 



SCIENCE- G OS SIP. 



CONDUCTED BY WILFRED 3IARK WEBB, F.L.S. 



Helix nemoralts and H. hortexsis in York- 

 shire. — Having recently visited an old chalk-pit 

 in the Yorkshire Wolds for II. nemoralis, which 

 occurs there in some variety, I send some notes on 

 the variation of this species within the very limited 

 space of about twenty square yards, together with 

 other notes on that species as found near Scar- 

 borough. In the old chalk-pit my attention was 

 first attracted to the varieties hyalozonata and 

 citronozonata, which together made up about 10 per 

 cent, of , the specimens present. In addition to 

 these varieties, albolabiata also occurs, having the 

 normal five or a less number of bands. The five 

 bands, when present, are thinner than usual, and 

 either the first or second is absent from about 

 50 per cent., though bandless forms are rare. In 

 colour they are all of the form libellula, with some- 

 times an inclination to the colour form of rubella. 

 All specimens are either of normal size or larger. 

 some exceeding an inch in diameter. The most 

 remarkable variation is in the weight of the shells. 

 Of some seventy specimens, taken at random, the 

 weights in decimals of an ounce are as follows : 

 five specimens weighed -02 each ; thirty-three, -03 ; 

 nineteen. -04 ; seven, -05 ; two, - 06 ; three, "07 ; 

 two, - 08 ; and one example, the heaviest of all, 

 turned the scale at T2 oz.. nearly two drams and 

 actually six times the weight of the lightest shells. 

 I need scarcely say that before weighing I had 

 been careful to remove every particle of animal 

 matter from the shells, which were all full-grown. 

 All the specimens having been taken from one small 

 chalk-pit. and at one visit, of course the variation 

 in weight cannot be explained by environment, or 

 varying climatic or local conditions. I presume it 

 is entirely due to age. the heaviest specimens, not 

 always the largest, being the most eroded. In 

 contrast to this narrow-banded heavy form are the 

 specimens which we commonly find here on the 

 sloping sea-cliffs. These shells show marked ten- 

 dency to coalescence in the banding. A hundred 

 specimens taken at random are banded as follows : 

 33 per cent. (12345), 40 per cent, (123) (45), 26 per 

 cent, have the five bands more or less distinct 

 and separate, whilst 5 per cent, are bandless libel- 

 lula, and all of normal weight. Variety rubella is 

 not uncommon in this district, and a pretty form 

 of var. libellula shows a dark clouding near the 

 margin. Var. castanea. so far as I know, does not 

 occur in the neighbourhood. Of band-varieties 

 here the formula 00300 is decidedly rare. Although 

 the largest specimens which I have found occur in 

 the old chalk-pit, the chalk formation alone is 

 probably not responsible for their size, as the very 

 smallest I possess, having deep black mouths, I took 

 at the Dane's Dyke, Flamborough. H. nemoralis 

 though common, is locally distributed here as else- 

 where. It occurs from just above highwater mark 

 on the sea-cliffs to the top of one at least of our 



higher moors, where a small colony thrives at 

 an elevation of six hundred feet on a bare stony 

 ridge where the stone curlew (Oedienemw gcolopax) 

 still breeds. H. nemoralis seems to differ in 

 habits in different districts. Here I have never 

 seen these snails climbing trees, which is a 

 general habit of the .species at Sledrnere in the 

 Wolds. H. hortensis is more generally distri- 

 buted than the former species, and shows a pre- 

 dilection for the hedgerows. If evidence were 

 needed to prove the specific distinctness of these 

 two helices, the occurrence of their varietal forms 

 in this district would prove useful. Here H. 

 hortensis. var. olivadea, is not uncommon, but the 

 complementary colour, variety castanea, in H. nemo- 

 ralis is, I believe, unknown. II. hortensis, var. 

 incarnate, I have sought here in vain, but H. nemo- 

 ralis, var. rubella, is fairly well distributed. During 

 the last five years a change has occurred in the 

 comparative abundance of some varieties of H. hor- 

 tensis, var. blivacea having become scarcer, and 

 var. arenicola much more common. In one locality 

 last year I found the latter variety to the number 

 of 70 per cent, in one ditch, and this year 50 per 

 cent, was the proportion in another district. — 

 W. Gyngell, 13 Gladstone Itoad. Scarborough. 



Palldestrixa jenkinsi. — On December 15th 

 Messrs. A. S. Kennard and B. B. Woodward made 

 an interesting communication to the Essex Field 

 Club regarding Pal uncstrina jenkinsi. This mollusc 

 has given rise to a good deal of controversy. First 

 of all, it had to be recognised that although Mr. 

 Edgar Smith described the species from specimens 

 found by Mr. Jenkins on the south side of the 

 Thames, Mr. Crouch had previously presented 

 examples to the British Museum from the north. 

 Many other localities have since been added, and 

 questions as to the introduction of P. jenkinsi 

 with timber from the Baltic, and so on, have been 

 raised. The form has not, however, been discovered 

 in any of the supposed original habitats abroad, 

 though two specimens have existed for a long 

 time under another name in the celebrated collec- 

 tion of British land and freshwater shells made by 

 the late Dr. Gwyn Jeftereys, and now, unfortunately 

 for us. in America. Messrs. Kennard and Wood- 

 ward have now made out a series of specimens 

 from a surface deposit on the Essex side of the 

 Thames of such depth as to point to their having 

 lived in this county early in, if not before, the 

 historic period. This disposes, once for all, of the 

 theory of recent introduction. 



COLOXIES "OP SXAILS AT HIGH ALTITUDES. — 



Up the romantic pass of the Winnats, above 

 Castleton, Derbyshire, at least 1,250 feet O.D., I 

 found a flourishing colony of Helix nemoralis, with 

 Helicigona arbustorirm and H. lapicida, under and 

 around broken pieces of carboniferous limestone. 

 On August 28, 1900. it was a very dry spot at the 

 time, there being no evidence of a spring or a 

 watercourse. H. lapicida had lost its periostracum. 

 I took very few specimens, as such a colony is 

 worthy of encouragement. Above Poole"s Cavern, 

 on a mound of fine concreted lime-ash from old 

 lime-works. I found evidences of the existence of 

 H. arbustorum, many bird-broken shells occurring. 

 This set me searching for the snail's habitat. 

 Though my first hunt was unsuccessful. I obtained 

 Vitrea glabra and V. alliaria among mossgrown 

 stones in an ancient watercourse. The U. glabra 

 there gave as strong a scent of gariic as does 

 V. alliaria. On a second visit I found the colonv 



