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A PPE N DIX.
SINCE the greater part of this work has been printed, M. Bouchard Chantreux has sent me his “Catalogue des Mollusques Terrestres et Fluviatiles du Pas de Calais,” which contains some interesting details on the habits and manners, and especially on the reproduction of these animals. Many of the facts recorded in this work must have been observed by most collectors of European shells; but they have been left for M. Bouchard to publish. From this work I shall make the following abstract : — He observes that the Arions and Limaces are semi-nocturnal animals; the eggs of Arions are separate, and covered with a hard calcareous coat, while those of the slugs (Limaces) are covered with a transparent coat, and often united together by a membrane like a string of beads. The land soles (Arion) lay about 70 to 100 eggs between May and September. They vary from 26 to 40 days in hatching, and the animals attain their full growth in a year; but they begin to deposit their eggs a month or two before that period. The young of A. ater is dull brown, with yellowish sides. The eggs of A. hortensis are very phosphorescent for the first 15 days after they are laid. M. Bouchard says that the true A. hortensis has no shell; he therefore doubts the species described by MM. Brard, Grateloup, Michaud, and Millet, which is said to produce Limacella concava; and I find that, by an oversight, I have referred this Limacella both to Arion hortensis and Limaa flavus. The eggs of the slugs (Limaces) are laid between May and September. They are hatched in about 25 or 30 days, and the young reach their full size near the end of the year. Limaa cinereus lays about 50 or 60, and Limaar agrestis is much more prolific, as it continues laying
from April to the end of November, depositing 30 to 70 eggs at each time; two individuals having laid 348 eggs in that period. The young grow very rapidly: he has seen specimens lay eggs on the 66th day of their age, when they did not reach their full size until the 92d day.
M. Bouchard describes a new species under the name of Limax arboreus, living generally on trees, especially such as are covered with moss. He thinks the Limax filans of Hoy is probably the young of this species. He describes the Limax brunneus as having great affinity to the dark variety of L. agrestis ; and he observes that the description and figures of Limacella concava of Brard exactly agree with the shell of this species.
The following table is formed from M. Bouchard's observations. The first column exhibits the time of laying, No. 1. standing for January; the second, the number of eggs laid at one time; the third, the number of days hatching; the fourth, the number of months before the animal arrives at its adult age.
--- arbustorum -
1. 2. 3. 4. 9-10 | 40—60 15-20 | 18–24 6- 9 | 60-80 20—30 13 7- 9 | 50 | 15—20 15–16 5–10 100-110 15-30 13 5–10 50— 80 15--20 11-13 5-10 50— 80 15-20 11-13
60— 80 13-15 10-11 7- 8 60- 90 14-15 11 9-10 40- 50 20 10-12 7- 9 10- 20 15—20 12 4- 9 40- 50 15 15-16 40- 50 20-25
11-14 7-11 40—60 20 7—10
35 – 40 15-20 5–9 20- 30 13-20
12 3— 9
30- 50 15-16 14 9-11 8- 15 15–20 8-10 5- 9 50— 70 14–15 | 11-12 5- 9 | 12– 15 15 1 13
10— 12 18–2022-24 7- 9 12- 15 15-20 12
Many of the species of Helices begin to reproduce before they reach their full growth.
The eggs of most of the Helices, of Bulimus obscurus, Clausilia nigricans, and Balea, are opake or opaline and isolated; those of H. virgata are transparent. The eggs of H. pulchella are united together into the form of a cup, often three or four times as large as the animal and its shell. Vitrina pellucida, and Succinea also, unite the eggs into a mass with a gelatinous matter : they are quite hyaline. The eggs of Bulimus obscurus are large; roundish oval : those of Clausilia nigricans are ovoid, and very large for the size of the animal, being nearly as large as the mouth of the shells: those of Balea are large and globular. He observes that H. virgata is very insensible to cold, for they do not hybernate even when the ground is covered with snow; and H. revelata lives in woods, on the young alders of two or three years' growth, eating the leaves, and resting on the under side of them during the heat of the day.
Deshayes (Lam. Moll. viii. 178.) refers the Turbo juniperi of Montagu to Pupa avena of Draparnaud, instead of Pupa secale, though he properly refers Vertigo secale of Dr. Turton's Manual to that species. He also, probably by a mere slip of the pen, has given England, among others, as the habitat for Pupa doliolum Drap. (Hist. viii. 183.)
The Conovulus denticulatus feeds on the detritus of marine plants and rotten wood; they lay 12 or 13 eggs in the month of June and September, united by a viscid matter into a small mass, which is fixed under the more humid stones. The eggs are globular, yellowish, and quite diaphanous: they are hatched about the 15th day, and the animals reach their full size about the end of the second year. They do not hybernate.
The following table respecting the eggs of Lymneadæ is drawn up from M. Bouchard's observations; the first column giving the form of the masses of eggs; the second,