HYGROMIA REVELATA. 43 
The MANDIBLE of H. occidentalis is figured by Moquin-Tandon and described as 
three-fourths of a millimetre in width, strongly arcuate, yellowish, extremities 
slightly dilated and very blunt, with a dozen feebly indicated, flat, and somewhat 
unequal ribs, which bluntly denticulate the concave margin. 
PD 
Fic. 62. Fic. 63. 
Fic. 62.—Jaw of Helix occidentalis Moquin-Tandon, highly magnified (after Moquin-Tandon). 
Fic. 63.—Jaw of an immature Hedix occidentalis from Tangiers, from a highly-magnitied micro- 
photograph by Mr. W. Bagshaw. 
The mandible from one of the immature Tangiers specimens is comparatively 
narrow, and shows twenty or more or less indistinctly defined ribs, which are 
grouped in assemblages of two, three or more ribs, and somewhat irregularly crenu- 
late the cutting margin, but show indications of a blunt median rostrum or beak. 
The RADULA of the immature Tangiers specimen shows a smaller and slenderer 
form of tooth than the British form, and the marginal teeth are less pectinate, a 
circumstance which, combined with the immaturity of the animal, does not tend to 
confirm the identity of the two forms. The count of the teeth is also somewhat 
different, showing 77 rows and 43 teeth in a row in the widest part. 
aby Cia 
Fic. 64.—Representative teeth from the radula of an immature shell of 1. occidentalis, Tangiers, 
after a highly magnified micro-photograph by Mr. W. Bagshaw. 
Habits and Habitats.—According to Moquin-Tandon, H. occidentalis is a very 
slow, sluggish, yet very sensitive animal, living mainly at the foot of trees and beneath 
bushes. Prof. Nobre remarks that it is rather common amongst plants by walls and 
on sandy soils, but is difficult to find when adhering to old walls; it, however, fre- 
quents damp as well as dry ground, as beneath stones on river banks; it is also 
found by the shore on walls or in rock-erevices, often in company with Clausilie 
and Pupe as at Viano, Foz, and Boa Nova near Lec¢a. 
Geographical Distribution.—This form, according to M. Bourguignat, is especially 
abundant in all countries bordering the Atlantic Ocean from Portugal, Spain, and 
France, to England. He also cites it for the centre of France, around Angers and 
Paris, and extends its range to Switzerland, Lombardy and the valleys of the Tyrol, 
as well as noting its reported occurrences in Algeria. 
Var. venetorum Bourguignat. 
Helix venetorum Bourg. ap. Locard, Cat. Gén. Faune Frang., 1882. 
SHELL depressed, and covered with very short hairs, which are quickly shed. 
Whorls flattened, but turgid at the sutures, the last long and descending very low. 
Aperture oblique, with approximating margins. Umbilicus perforate. Diam., 
8 mill. ; alt., 5 mill. 
France—(Westerlund, Binnen-Conchylien, 1889, p. 62). 
Portugal— Povoa de Varzin, Minho (Westl., Binnene., 1889, p. 62). 
Var. villula Bourguignat. 
Helix villula Bourg. ap. Locard, Cat. Gén. Faune Frang., 1882. 
SHELL depressed and almost flat, densely covered with oblique rows of very 
long hairs. _Whorls convex, very rapidly increasing in size, the last somewhat 
dilated and gradually descending in front. Aperture relatively very ample.  Peris- 
tome with margins somewhat convergent and reflected basally around the somewhat 
open umbilicus. Diameter attaining to 8 mill. 
France and Portugal—(Westl., Binnenc., 1889, p. 62). 
