TURBINATED SHELL-FISH. 



359 



obliged to those men who contemplated some- 

 thing more than the outside of the objects be- 

 fore them. To Reaumur we are obliged for 

 examining the manners of some with accura- 

 cy; but to Svvammerdam for more. In fact, 

 this Dutchman has lent an attention to those 

 animals that almost exceeds credibility; he 

 has excelled even the insects he dissected, in 

 patience, industry, and perseverance. It was 

 in vain that this poor man's father dissuaded 

 him from what the world considered as a bar- 

 ren pursuit : it was in vain that an habitual 

 disorder, brought on by his application, inter- 

 rupted his efforts; it was in vain that mankind 

 treated him with ridicule while living, as they 

 suffered his works to remain long unprinted 

 and neglected when dead: still the Dutch 

 philosopher went on, peeping into unwhole- 

 some ditches, wading through fens, dissecting 

 spiders, and enumerating the blood-vessels of 

 a snail : like the bee, whose heart he could 

 not only distinguish, but dissect, he seemed 

 instinctively impelled by his ruling passion, 

 although he found nothing but ingratitude 

 from man, and though his industry was appa- 

 rently becoming fatal to himself. From him 

 I will take some of the leading features in the 

 history of those animals which breed in shells ; 

 previously taking my division from Aristotle, 

 who, as was said above, divides them into 

 three classes: the Turbinated, or those of the 

 Snail-kind ; the Bivalved, or those of the 

 Oyster-kind; and the Multivalved, or those 

 of the Acorn-shell kind. Of each I will treat 

 in distinct chapters. 



CHAP. V. 



OF' TURBINATED SHELL-FISH, OR THE SNAIL 

 KIND. 



To conceive the manner in which those ani- 

 mals subsist that are hid from us at the bot- 



guineas. The Turbo Scalaris. if large and perfect, is 

 worth a hundred guineas; the Cypraea Aurantium, with- 

 out a hole beaten through it, is worth fifty ; and it has 

 been calculated, that a complete collection of the British 

 Conchology is worth its weight in pure silver. In an 

 economical and political view, they are of no inconsi- 

 derable import. Pearls, the diseased excrescences of 

 mussels and oysters, iurm a portion of the revenues of 

 these and some other kingdoms; and constitute, with 

 jewels, the rich and costly ornaments by which tlie high 

 and wealthy ranks of polished society are distinguished. 

 The Cypraea Moneta, or money cowry, forms the current 

 coin of many nations of India and Africa; and this co- 

 vering or coat of an inconsiderable worm, stands at this 

 day as the medium of barter for the liberty of man; a 

 certain weight of them being given in exchange for a 

 slave. The scholar needs not the reminiscence, that the 

 sufl'rages of the ancient Athenians were delivered in, 

 marked upon a shell ; the record of which is still corn- 



torn of the deep, we must again have recourse 

 to one of a similar nature and formation that 

 we know. The history of the garden-snail 1 

 has been more copiously considered than that 



memorated in the derivation of our terms, testament and 

 attestation . 



1 Garden Snails. The most common in this country 

 of herbivorous Trachelipods, is the Garden-snail ; but 

 the species whose history has been most copiously rela- 

 ted, is that called in France the Escaryot, which, though 

 stated to have been originally imported into this coun- 

 try, now abounds in some parts of Surrey, and other 

 southern countries. On the continent, especially in 

 France, this large snail, which is more than double the 

 size of our garden one, is used as an article of food, and 

 though said not to be easy of digestion, is very palatable. 

 They are thought to be in best season in the winter, 

 when they are invested with their temporary calcareous 

 covering, which falls off in the spring. 



Early in the spring, snails lay, at different times, a 

 great number of white eggs, varying at each laying from 

 twenty-five to eighty, as large as little peas, enveloped 

 in a membraneous shell, which cracks when dried. They 

 lay these eggs in shady and moist places, in hollows 

 which they excavate with their foot, and afterwards, 

 cover with the same organ. These eggs are hatched 

 sooner or later, according to the temperature, producing 

 little snails, exactly resembling their parent, but so de- 

 licate that a sun-stroke destroys them, and animals feed 

 upon them; so 'that few,^comparatively speaking, reach 

 the end of the first year, when they are sufficiently de- 

 feuded by the hardness of their shell. 



The animal, at first, lives solely on the pellicle of the 

 egg from which it was produced. This pellicle, con- 

 sisting of carbonate of lime, united to animal substance, 

 is necessary to produce the calcareous secretion of the 

 mantle, and to consolidate the shell, as yet too soft for 

 exposure. When this envelope is eaten, the little snail 

 finds its nutriment, more or less, in the vegetable soil 

 around it, and from which it continues to derive materials 

 for the growth and consolidation of the shell. It remains 

 thus concealed for more than a month, when it first issues 

 forth into the world, and attacks the vegetable produc- 

 tions around, returning often to an earthly aliment, pro- 

 bably still necessaiy, for the due growth and hardening 

 of its portable house. 



These snails cease feeding when the first chills of 

 autumn are felt ; and associating, m considerable num- 

 bers, on hillocks, the banks of ditches, or in thickets and 

 hedges, set about their preparations for their winter re- 

 treat. They first expel the contents of their intestines, 

 and then concealing themselves under moss, grass, or 

 dead leaves, each forms, by means of its foot, and the 

 viscid mucus which it secretes, a cavity large enough to 

 contain its shell. The mode in which it effects this is re- 

 markable: collecting a considerable quantity of the mucus 

 on the sole of its foot, a portion of earth and dead leaves 

 adheres to it, which it shakes off on one side ; a second 

 portion is again thus selected and deposited, and so on 

 till it has reared around itself a kind of wall of sufficient 

 height to form a cavity that will contain its shell ; by 

 turning itself round it presses against the sides and 

 renders them smooth and firm. The dome, or covering, 

 is formed in the same way: earth is collected on the foot, 

 wlu'ch theu is turned upwards, and throws it off by exud- 

 ing fresh mucus ; and this is repeated till a perfect roof 

 is formed. Having now completed its winter-house, it 

 draws in its foot, covering it with the mantle, and opens 

 its spiracle to draw in the air. On closing this, it forms 

 with its slime a fine membrane, interposed between the 

 mantle and extraneous substances. Soon afterwards, 

 the mantle secretes a large portion of very white fluid 

 over its whole surface, which instantly sets uniformly, 



