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HELIX LAMELLATA-(the Plated Snail) (Pl. VII., fig. 51)-is a characteristic northern shell. It inhabits woods, on decaying leaves of Luzula and fronds of Lastrea, &c., and about rocks near running water. It was first discovered near Scarborough, and is now known throughout the North of England, the North and West of Scotland, and the North of Ireland. Until recently, this species was peculiar to North Britain, but it has been found in North Germany and in Sweden.

This beautiful conical globose shell is only one-tenth of an inch high and broad, of greyish colour; and in certain lights it exhibits a satiny appearance, which is due to the action of the rays of light upon the fine, sharply-cut stria which cover its surface.

HELIX ACULEATA-(the Prickly Snail) (Pl. VII., fig. 48). This, also, is a minute species, and differs especially from the last in the epidermis. of the shell being raised into from twenty to thirty plaits, which rise in the middle of each whorl to a sharp point. Fresh specimens are exquisitely beautiful objects, exhibiting the appearance of a coronet of bristles encircling each whorl.

This species is so minute, and its colour so closely resembles that of the dead leaves upon which it is usually found, that it is detected with

difficulty, and it is advisable to lift the leaves and turn them over in the hand to find it. In Gloucestershire it is found on the under sides of the leaves of the hazel; it is occasionally seen on liver-worts (Jungermannia). H. aculeata is distributed throughout Britain and Europe.

HELIX POMATIA—(the Apple Snail) (Pl. VIII., fig. 73). This snail is commonly regarded as the one which was held in so great repute by the epicures of ancient Greece and Rome; but this is not the fact, for a larger species replaces H. pomatia in Southern Europe. In the North of France and in Switzerland the Apple Snail, however, is a much-prized mollusk as an article of diet.

The shell of this species, the largest of our British snails, is globular, thik, and strong, of a yellowish-white, with spiral bands of brown ; it is as much as two inches in breadth and height; the whorls are five in number, the last one extremely large and inflated.

This, the largest snail, possesses the greatest number of teeth among the Helicidæ, and they are only exceeded in number by those of the Limaces; the number is 21,140, contained in 140 rows. of 151 each. The jaw (fig. 21) is strongly arched, with a moderate number of

Fig. 21.-Jaw of H. pomatia.

[blocks in formation]
[graphic]

79

Vincent Brooks, Imp

prominent ribs, which form strong teeth on the free margin.

H. pomatia is to be met with on the borders

copses

of and woods on a calcareous soil. It is found at Sevenoaks, in Kent; Croydon, Reigate, and Dorking, in Surrey; in Hertfordshire, Oxfordshire, and Wilts; it is common on the Cotswold range. In early spring these snails unite for propagation. The eggs are globular, and covered with a white opaque skin, and are about the size of small peas; these are laid in a kind of nest, made in the loose earth, in the months of June and July. The eggs are hatched in twenty to thirty days, according to the season and temperature; when first excluded, the young live solely on the egg-cases; at the end of the year they are about the size of Helix hispida, and arrive at maturity in a little more than a

year.

The Apple Snail, on the arrival of the period of hybernation, constructs, by the aid of its large muscular foot, and a very glutinous secretion, a hole in the ground, just large enough to receive the shell; this it lines with dead leaves, retires to its hybernaculum, and closes the aperture of the shell with a solid calcareous plate, secreted and formed by the mantle; it then withdraws considerably within the shell, and the more effectually to exclude the cold air, forms

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