Part 5

H. (Heliomanes) virgata (i.e. striped).--A very variable shell. See the illustration above of some at rest on thistles. Local, but very abundant where found. Whitish shell with dark bands, but a yellowish and a white variety usually is found with the type. The most beautiful variety, radiata, is chiefly found in Romney Marsh, and from Hythe to Rye.

H. (Turricola) terrestris.--A Mediterranean species, well established since 1890, in one spot near Dover. A pyramidal shell, greyish, with one dark band on each whorl.

H. (Cochlicella) barbara (i.e. foreign).--Long, conical, whitish, with one dark band. By the sea-coast. In shape somewhat like a Buliminus.

We come now to the Pupa family and its genus Buliminus and its sub-genus Ena. It is represented by:--

Ena montana.--A local and southern shell, conical, slightly glossy, brown. Lip white and deflected. Commonly found on the holes of smooth-barked trees, and it closely resembles the small knobs on beech trunks.

Ena obscura.--Like the former, but much smaller, and found nearly everywhere in England and Wales. Found in hedgebanks, or on beech trunks. Its specific name is derived from its habit of covering itself with a coating of earth, and so becoming inconspicuous.

The plate on p. 47, gives figures of some of our smaller shells, enlarged in most cases so that their distinguishing marks can be seen. The upright line by the side of each figure gives its actual height. The shells as numbered are Helix rupestris, H. pygmæa, H. pulchella, H. lapicida, H. obvoluta, H. terrestris, H. barbara, Ena montana, Ena obscura, Pupa secale, P. anglica, P. cylindracea, P. muscorum, Vertigo antivertigo, V. moulinsiana, V. pygmæa, V. alpestris, V. substriata, V. pusilla, V. angustior, V. edentula, and V. minutissima. Without a magnifying glass it will be seen that it would be very hard to distinguish some of the minute shells, but this enlargement enables us to see the characteristic denticles in the mouth, and the presence or absence of striations on the shell.

Pupa (Abida) secale is named from the Latin for rye, a grain of which the shell more or less resembles. Conical, brown, mouth horseshoe-shaped with eight white denticles. Our largest Pupa. Local, but abundant where found. Prefers calcareous rocks or woods.

Pupa (Lauria) anglica.--Small, ovate, purplish in colour; mouth like that of secale. Lives in moss, mainly in the north of Britain.

Pupa (Lauria) cylindracea.--Small, cylindrical, paler than the last; thick and reflected white lip with one denticle. Abundant. On stones, in moss, under leaves and bark.

Pupa (Jaminia) muscorum.--Common, especially on sandy soils near the sea. Mouth nearly circular, whereas in the two former species it is horseshoe-shaped. The lip is thin and not reflected.

The genus Vertigo (i.e. twisted, the Latin equivalent of the Greek Helix) contains shells even smaller than the Pupæ, about the size of a pin's head.

Vertigo (Alæa) antivertigo (i.e. not reversed or sinistral, as are V. pusilla and V. angustior). Semi-transparent, glossy, horn-colour, with denticles (as have all except V. edentula and V. minutissima). Found in nearly all counties in moist places.

Vertigo (Alæa) moulinsiana.--Our largest species, though only 2-1/3 millimetres in height. Mainly in marshy places. Not common.

Vertigo (Alæa) alpestris.--Rare and local, chiefly northern. Nearly transparent shell.

Vertigo (Alæa) pygmæa.--Common, and often in colonies at roots of grass and under stones and logs. Not confined to moist places.

Vertigo (Alæa) substriata.--Local. Strongly striated.

Vertigo (Vertilla) pusilla.--Sinistral, as is also

Vertigo (Vertilla) angustior.--Both species rare and local. The former is the larger and broader. In the former the last whorl is broadest, in the latter the penultimate. In the former the mouth is semi-oval, in the latter triangular. In the former the outer lip is very slightly, in the latter very deeply contracted. The former has 6 to 7 teeth, the latter 4 to 5.

Vertigo (Sphyradium) edentula is dextral and without denticles. Perhaps the most common Vertigo. Partial to bracken.

Vertigo (Isthmia) minutissima.--Dextral and without denticles. Smaller, narrower, and more strongly striated than edentula, but rarer. All the Pupæ should be examined with a magnifier.

Balea perversa (i.e. sinistral) is a much larger shell belonging to the Clausilia family. Thin, dark horn-colour, semi-transparent, glossy, 7 to 8 whorls, local, but abundant where found. Chiefly found on trees.

Clausilia (Pirostoma) bidentata.--All our British clausilias are sinistral. The clausilium (little door) is an internal contrivance fastened to the pillar of the shell (whereas an operculum is attached to the body of a mollusc) by an elastic ligament to protect it against insect enemies when the animal withdraws. Bidentata has two denticles, fusiform and reddish-brown, as are all. Very common on walls and trees.

Clausilia (Pirostoma) rolphii.--Rare and local. Almost subterranean in habit. More coarsely striated than the last. The upper whorls nearly of the same breadth, forming a short cylinder.

Clausilia (Alinda) biplicata.--Very local. Chiefly on Thames willows. Larger than the two former, and streaked with white.

Clausilia (Marpessa) laminata.--Much like the former, but widely distributed. Usually found on beech and ash trees, and on limestone rocks. Smooth and glossy.

In the family Stenogyra we have three genera, Azeca, Cochlicopa, and Cæcilioides (with also the imported Stenogyra Goodallii, found only in pine-houses).

Stenogyra (Azeca) tridens is a small chrysalis-shaped, solid but semi-transparent shell, horn-coloured, with 3 denticles. Not rare in moist places.