354 



Helix.- 



-MOLLUSCA.- 



-BULIMI'S. 



eemilunar, or roundish. The margins are distinct, and 

 the peristome is thicliened or reflected. 



The species of True Snails are very numerous ; and 

 as they present a great man}' variations of form and 

 general appearance, they have been divided into many 

 genera. — See Plates 6 and 7 (several genera and 

 species). Including these, the number of described 

 species exceeds twelve hundred, while some hundreds 

 more have not )'et been characterized. The}' are 

 world-wide in their distribution, being found in all parts 

 of tlie globe, in Europe, Asia, Africa, both Americas, 

 and Australia. To the north they are found ranging 

 as far as the limit of trees, and to the south they extend 

 to Terra-del-Fuego. They are most abundant, how- 

 ever, in warm countries and moist situations. " M. 

 d'Orbigny observed six species at elevations exceeding 

 eleven tliousand feet in South America ; and Layard 

 found //. gardeneri at the height of eiglit thousand feet 

 in Ceylon."— (irooAra/'f/.) They are most active by 

 night, and that is their chief season for seeking their 

 food. This consists of vegetable substances, and, like 

 the Slugs already mentioned, they frequently commit 

 great devastations in our fields and gardens. The most 

 destructive species, perhaps, in this country is the 

 common garden snail, Ihlix aspersa; while in the 

 wine countries of France, the Roman snail, H.j'omatia, 

 is very destructive to tlie vine, especiall}- when it is 

 just putting forth its tender buds and first leaves. 

 Snails are truly hermaphrodite, each individual uniting 

 both sexes in itself; tliey are not self-impregnating, 

 however, the union of two individuals being necessary 

 for the propagation of the species. On the right side 

 of the neck, containeil within a small cavity, we find 

 several small bodies of a horny ci-ystalline substance 

 called darts. They are shaped somewhat like a bay- 

 onet ; and during the love season, according to popular 

 accounts of the snail and its doings, the animals are 

 said to shoot these darts at each other from their quiver, 

 when the two individuals are about two inches apart. 

 " The existence of the darts," says Dr. Johnston, " in 

 some few species of Helix is certain ; while the power 

 of the sn.ail to throw them from its reservoir is ima- 

 ginary!" Their eggs are pretty numerous, and in general 

 are spherical or oval. The outer coat is opaque and 

 hard, consisting of carbonate of lime, the particles of 

 which are gradually and successively deposited over 

 the whole of its inner surface. The Roman snail, H. 

 pomatia, deposits only about fifteen eggs, while our 

 common species lay from thirty to fifty. Generally 

 they are deposited one by one, but placed in little heaps, 

 and their colour is usually bluish-white or pure milk- 

 white. Snails are long-lived, and have a wonderful 

 degree of tenacity of life. Many interesting instances 

 are recorded of the resuscitation of snails, after having 

 undergone a long suspension of their vital powers. One 

 of the most wonderful examples of this recovery from a 

 "long slumber" has been related by the writer of this 

 artich-' in the Annals and Magazine of Natural History 

 for 1850. The individual alluded to was a species of 

 the snail of the desert, //. dcsertorum, brought from 

 Egypt, and attached to a tablet in the British Museum 

 on tlie 25th of March, 1846. In this imprisonment it 

 remained for four years, ha-«ing been discovered on the 



7th March, 1850, attempting to escape from " durance 

 vile." The shell being removed from the tablet and 

 placed for a few minutes in tepid water, the animal 

 completely revived and lived for more than twelve 

 months afterwards. In cool or cold climates snails 

 become torpid in winter. They retreat, before the cold 

 has benumbed their powers, into some snug quarters 

 under stones, clods of earth or moss, or in crevices of 

 old walls, &c. Some dig into the ground, forming an 

 excavation or nest in which they bury the shell, and 

 then close the aperture with a sort of temporary oper- 

 culum of a thick calcareous nature, called an epiphragm. 

 Here they remain till the return of spring calls them 

 forth again from their state of hybernation. In hot 

 climates a similar degree of torpidity takes place ; and 

 during this state of estivation, as it is called, they remain 

 perfectly quiescent, and form the same kind of oper- 

 culum, or epiphragm, to protect them from the drying 

 effects of the external atmosphere. Snails afford food 

 to some kinds of birds, as the missel-thrush, &c., and 

 in their turn are often eaten by omnivorous man. At 

 the present day they are comparatively little used as 

 an article of food ; but amongst the ancient Romans, 

 the //. pomatia (hence called the Roman snail) was 

 in great request, " not from any peculiar relish for such 

 tasteless food, but from a belief in their aphrodisiacal 

 virtue." — (Johnston.) The snails were kept in depots 

 called Cocldearia, and fattened carefully with a "cer- 

 tain paste made of cuit and wheat meale." — {Ilolland^s 

 Pliny.) The same author states, on the witness of M. 

 Varro, th.at these snails grew to an enormous size. In 

 Sicily several species of Helix are eaten, and the Bra- 

 zilians are said also to eat snails. In this country and 

 in France they are used for their supposed virtues in 

 diseases of the chest and lungs. 



The Genus Succinea. — The Amber Snails have a 

 thin, ovate, or oblong shell, with a short spire and a 

 large aperture. It is not umbilicated, and the peris- 

 tome is simple and sharp. It is generally of a delicate, 

 horny, or amber colour. The animals are of a vesicular 

 structure, are large compared with the size of the shell, 

 and are not quite retractile within it. The species are 

 rather numerous, about seventy having been described, 

 and are found in all the four quarters of the globe, 

 though more especially abounding in temperate climates. 

 They are amphibious in their habits, living amongst 

 plants in damp situations, but rarely entering the water. 



Genus Bultmus. — See Plate 7, fig. 3 [Bulimus 

 ovatus). The Bulimi are animals of a moderate size, 

 inclosed within the shell, which is oblong or turreted, 

 and composed of many whirls. The aperture is longer 

 than wiile; the peristome is tliin or reflected, rounded 

 in front, and in many species the shell is umbilicated. 

 The species are very numerous, upwards of six hundred 

 and fifty having been described. The)' are found in all 

 parts of the world, and vary much in shape and appear- 

 ance. Like the Helices, these animals abound most in 

 warm climates, and, like them, pass the dry season in a 

 sort of torpor or deep slumber, buried at the roots of 

 trees, in moss, or in the thick brushwood, and having 

 the mouths of their shells covered with a pretty solid 

 epiphragm. They have the same power also, as the 

 Helices, of undergoing long fasts ; and instances have 



