In August 1863, Mr. W. J. Sterland[84] put specimens of H. nemoralis in a box and afterwards placed the box in his cabinet; in November 1866 one specimen was discovered to be alive.
Gaskoin relates[85] a case in which specimens of H. lactea were purchased from a dealer in whose drawer they had been for two years. This dealer had them from a merchant at Mogador, who had kept them for more than that time under similar conditions. One of these shells on being immersed in water revived, and in April 1849 was placed quite alone under a bell jar with earth and food. In the end of the following October about thirty young H. lactea were found crawling on the glass.
Mr. R. D. Darbishire bought[86] some H. aperta in the market at Nice on 18th February 1885. Two specimens of these, placed with wool in a paper box, were alive in December 1888. This is a very remarkable case, H. aperta not being, like H. desertorum, H. lactea, H. Veatchii and Bul. pallidior, a desert snail, and therefore not accustomed to fasting at all.
Age of Snails.—It would appear, from the existing evidence, which is not too plentiful, that five years is about the average age of the common garden snail. Mr. Gain has published[87] some interesting observations on the life of a specimen from the cradle to the grave, which may be exhibited in a tabular form.
| Aug. 1882. | Eggs hatched; one attained diameter of ⅜ in. before winter; fed on coltsfoot and cabbage. |
| 5th Oct. 1883. | Shell 1 in. in diameter, no lip formed. |
| July 1884. | Shell finished; diameter 1⅛ in., including perfect lip. |
| 3rd May 1885. | Left winter quarters; companion introduced, with which it was seen in company on 5th August. |
| 9th Aug. „ | Laid eggs in soil, which were hatched on 10th September, and feeding on 17th September; in May 1886 the largest of these was 11/16 in. diameter. |
| 13th Oct. 1887. | Old snail died, aged 5 years 2 months. |
According to Clessin, the duration of life in Vitrina is one year, Cyclas 2 years; Hyalinia, Succinea, Limnaea, Planorbis, and Ancylus are full grown in 2 to 3 years, Helix and Paludina in 2 to 4, and Anodonta in 12 to 14. Hazay finds[88] that the duration of life in Hyalinia is 2 years, in Helix pomatia 6 to 8, in Helix candicans 2 to 3, in Paludina 8 to 10, in Limnaea and Planorbis 3 to 4.
Growth of the Shell.—Mr. E. J. Lowe, many years ago, conducted[89] some interesting experiments on the growth of snails. The facts arrived at were—
(1) The shells of Helicidae increase but little for a considerable period, never arriving at maturity before the animal has once become dormant.
(2) Shells do not grow whilst the animal itself remains dormant.
(3) The growth of shells is very rapid when it does take place.