XEROPHILA VIRGATA. 153 
The effects of a different environment is often strikingly displayed in 
the shell. ‘The uniformly dull white shell is induced by continued 
exposure to ardent sunlight on dry and arid ground, such shells are regarded 
as essentially characteristic of hot desert regions, the thick whitish shell 
reflecting the heat to which it is exposed, and therefore tending to more 
effectually conserve the essential moisture of the animal inhabitant. 
Pigmentation attains its extreme development in the var. negrescens, in 
which the whole surface of the shell is very dark and more largely com- 
posed of animal matter. In its most characteristic state it may easily be 
mistaken for Hygromia hispida. his form is connected with the dull 
white form by the varieties »u/fula, lutescens, ete. 
VARIATIONS IN FORM OF SHELL. 
Var. conica Germain. 
Heltx pilula var. conica Germain, Feuille jeunes Nat., p. 102. 
Helix variabilis vars. E, ¥, and D (in part), Gassies, Moll. Agenais, 1849, p. 79. 
Helix lineata var. major Bourguignat, Mal. Alger., 1864, vol. i, p. 219, pl. 24, f. 30. 
SHELL very conical in shape. Well marked shells of this 
variety have an altitude quite equal to or even exceeding 
their diameter. 
The var. eoniea is described as being as broad as high, 
very markedly conical, quite convex below, suture somewhat 
deep. Diam., 10 mill. ; alt., 9 mill. 
The sub-var. major Bourguignat. The type figure is very he oe eee 
conoid and shows a diameter and altitude of 15 mill. Gah aera eesti 
The var. E of Gassies is very conical, but zoned asin the (4. /xeata var. major 
typical. XY. variabilis. The var. F of Gassies is also very pee rae Rauied 
conical, of a fawn or yellowish-grey in colour with an inter- sits (after Bourg.) 
rupted paler keel-line. The var. D of Gassies is described as ‘conical, white, 
peristome very thick.” The very thick peristome, as well as the character of the 
pigmentation, are, however, characters not necessarily correlate with form variation. 
BRITISH DISTRIBUTION. 
This variety is not common, but widely dispersed. 
In England, it has been noted at Weston-super-Mare, Somerset, by Mr. J. 
Madison ; at Bridport, Dorset, by Mr. Deakin ; at Blaxhall, Suffolk, by Mr. G. T. 
Rope ; and at Dymchurch, Kent, and Filey, Yorkshire, by Mr. W. E. Brady. 
In Wales, it has been found at Rhyl, Flintshire, by Mr. W. H. Boland; at 
Colwyn Bay, Denbigh, by Mr. Brady; and at South Cliff, Tenby, Pembrokeshire, 
by Mr. A. G. Stubbs. 
In Ireland, it was collected by Mr. P. H. Grierson at Barmeath, Louth, and 
Ennistymon, Clare ; and by Mr. A. W. Stelfox at Earawalla Point and Dogs Bay, 
Galway, the latter very characteristic specimens. 
FOREIGN DISTRIBUTION. 
In France, Dr. Gassies has found the varieties he describes in the Agenais, but 
especially notes the var. F as found on a bank of lacustrine marl of 3rd century age 
at St. Julien de Fargues, Landes ; and the var. conica Germain is recorded as rare 
at Puy, near Dieppe, Seine Inférieure. 
In Algeria, M. Bourguignat records his H. lineata var. major from Alger. 
Var. subglobosa Jeffreys. 
Helix virgata var. subglobosa Jeffreys, Brit. Conch., 1862, vol. i, p. 210 (pars). 
Helix virgata var. inflata Westerlund, Faunen Palzarct., 1889, p. 166. 
Helix virgata var. variabilis f. turgida Blanc. and Westl., Westerlund, op. cit. 
Helix virgata var. variabilis f. tumida Westerlund, in Kobelt’s Rossm. Icon., 1877, 
vol. v, f. 1299. 
Helix virgata var. variabilis f, variata Westerlund, Faunen Palzarct., 1889, p. 166. 
Helix virgata var. dilatata Sikes, mss. 
The var. subglobosa is more globose, last whorl larger in proportion to the rest. 
Dr. Jeffreys included in his description of this variety the not necessarily corre- 
lated characters of ‘‘smaller, with a double band above the periphery,” which I 
have excluded, 
