from the mouth, and may be seen in position by breaking off the outer part of the last whorl; it* consists of a thin, spoon-shaped shelly plate attached to the folds of the columella by an elastic filament. When the animal comes out of the shell, the clausium is pushed against the columella; and the elasticity of its filament also admits of it closing the aperture on the snail withdrawing within the shell. The clausium is not secreted until the snail is about to complete its shell; and is not attached to the animal, but is merely an appendage to the mouth of the shell.

About 300 species of Clausilo are known, the majority of which inhabit South-eastern Europe. Clausila is represented in the Upper Eocene of the Isle of Wight; and the four species at present living in England, also found fossilized in the newer Tertiary deposit of Essex, are as follows:

CLAUSILIA BIPLICATA-(the Folded Close Shell) (Pl. IX., fig. 95)—is larger than any of its congeners. The shell is two-thirds and occasionally three-fourths of an inch in length, with about

twelve whorls; it is slender and thin, of a reddish or greyish-brown colour, with raised white lines; there are two folds on the columella.

C. biplicata is very rare, and was first described as British by Montagu. It may be found in some abundance under the larger osiers bordering the banks of the river Thames about Hammersmith. In the winter it buries the front of the shell in the loose soil among the tufts of grass or at the base of the trees. It is also recorded from two localities in Wiltshire.

CLAUSILIA LAMINATA (the Laminated Close Shell) (Pl. IX., fig. 87).-The shell is large, handsome, and at once distinguished by its polished appearance; it is usually semi-transparent, glossy, yellowish- or reddish-brown, and sometimes greenish-white and transparent. There are twelve whorls; the aperture is oval, with two folds, from which latter character it is known as C. bidens, one of them curved and situated on the middle of the columella-lip, and the other is straight and near the top of the aperture; in addition there are three or four folds deep within the aperture, which are visible from the outside, owing to the transparency of the shell. The shell attains a length of three-fourths of an inch, but it varies in size and colour. The dentition is thus:-Number of rows, 120; number of teeth in a row, 51; total, 6,120.

This elegant species is local, and chiefly confined to the southern counties in England, reaching the limit of its northern distribution in Hulne Woods, Alnwick; it is rare in Ireland. C. laminata is especially met with in woods on a limestone soil; it is gregarious on the trunks of beech and other trees, during the night and after rain.

The eggs of this snail are very large in proportion to the animal, and are deposited among decaying wood in the autumn, to the number of ten or twelve; the young appear at the end of twenty days, and do not attain the adult state until the end of the second year.

CLAUSILIA RUGOSA-(the Rugose Close Shell) (Pl. IX., fig. 91).-This species is also known under the names of C. nigricans and C. perversa; it is the commonest of the Clausilia, and lives on walls, about rocks, and under stones, and on the trunks of beech and ash in woods.

The shell is more or less fusiform or spindleshaped, of about half an inch in length, and composed of nine or ten, and not unfrequently twelve or thirteen whorls; the colour varies from a very pale greyish-white to a deep reddish-brown; greenish-white specimens are of rare occurrence; the shell is streaked with lines of grey, and striated obscurely or prominently in different individuals. The peristome is thickened, detached