MONOGRAPH OF BRITISIE LAND AND FRESHWATER MOLLUSCA. 455 
Vitrina pellucida (Miiller). 
1765 Helix domestica Strom, Trondhj. Selsk. Skrift., iii., p. 435, pl. vi., f. 15. 
Synonymy. —'l'o the various names included amongst the synonyms of 
this species, a few others may be added on the authority of reputable 
authors, amongst which are Cobresia Helicoides vitrea of Hiibner; Limacina 
pellucida Hartmann; //yalina pellucida Studer; Vitrinus pellucidus 
Mont. : and Helicolimaax pellucida of Férussac. 
The Helix domestica of Strém, too, is almost surely identical with V7trina 
pellucida. It is described as follows :— 
Original Description.—‘‘ Helix domestica. This name I give to a little snail, 
which is represented by fig. 15, since I find nothing in Linné’s Systema Nat. to 
which [ can with certainty refer it. It is small, ovate- 
rounded, and somewhat convex above, and shows three small CD ® 
and flat whirls on the one side. The aperture is large and 
may be called almost entirely round, and the columella, or Fic. 522, — Helix 
domestica Str. (after 
part attached to the snail’s house, comprises a small segment, Strém) 
or may be inscribed in an exact circle. The shell is yellowish, : 
and so brittle that one cannot pick it up without breaking it in pieces. It contains 
a bluish snail. It is found in great numbers under the moss or turf on houses, and 
is sometimes fully as large as the figure, which represents both the upper and 
lower sides.” —HANS StTr6M, Trondhj. Selsk. Skrift, 1765, iii., p. 435, pl. vi., f. Lo. 
Enemies.—'his species has been observed though rarely at 'l'hrush- 
stones in North Lincolnshire, by the Rev. E. A. Woodruffe-Peacock. 
Geographical Distribution. — The number of counties or vice- 
counties for which the occurrence of V. pellucida has never been verified 
have been diminished, as it has now been found in North Wiltshire in 
England by Mr. Swanton; Carlow in Ireland by Mr. Phillips; South 
Ebudes by Rev. J. E. Somerville ; while North Aberdeen in Scotland, was 
added in the course of our investigations into the northern range of our 
mollusea, by the aid of a government grant for that purpose. 
he record of the occurrence of the var. depressiuscula Jeffr., at Collon, 
co. Louth (see p. 9), has reference to Vitrina hibernica, and not to the 
present species. 
Our knowledge of its continental distribution has also been increased 
by its reported occurrence in South Holland and Utrecht, Netherlands ; 
and at Solothurn in Switzerland. 
GENUS HYALINIA Charp. 
Sun-Genus Huhyalinia Albers. 
The species of this group are, as pointed out by Prof. Gwatkin, a very 
distinct section, differing by the character and number of the radular 
teeth from the nitidula group. 
The Rey. E. W.W. Bowell in a suggested arrangement of the Huhyalinie 
hased upon their anatomical structure, links together as having the most 
intimate relationship, Aibernica and scharffi; also cellaria and rogerst; and 
finally helvetica and alliaria. 
Mr. Bowell also states that he believes that the great variation in the 
genitalia and radula observed within the limits of certain species is due 
largely to the species hitherto recognized being composite. 
