362 



HISTORY OF FISHES. 



cover, it sleeps during the winter ; and, for 

 six or seven months, continues without food or 

 motion, until the genial call of spring breaks 

 its slumber, and excites its activity. 



The snail, having slept for so long a season, 

 wakes one of the first fine days of April, 

 breaks open its cell, and sallies forth to seek 

 for nourishment. It is not surprising that so 

 long a fast should have thinned it, and ren- 

 dered it very voracious. At first, therefore, 

 it is not very difficult in the choice of its food ; 

 almost any vegetable that is green seems wel- 

 come ; but the succulent plants of the garden 

 are chiefly grateful ; and the various kinds of 

 pulse are, at some seasons, almost wholly des- 

 troyed by their numbers. So great is the 

 multiplication of snails in some years, that 

 gardeners imagine they burst from the earth. 

 A wet season is generally favourable to their 

 production ; for this animal cannot bear very 

 dry seasons, or dry places, as they cause too 

 great a consumption of its slime, without 

 plenty of which it cannot subsist in health and 

 vigour. 



Such are the most striking particulars in 

 the history of this animal ; and this may serve 

 as a general picture, to which the manners 

 and habitudes of the other tribes of this class 

 may be compared and referred. These are, 

 the sea-snail, of which naturalists have,, from 

 the apparent difference of their shells, men- 

 tioned fifteen kinds; 1 the fresh-water-snail, of 

 which there are eight kinds; and the land- 

 snail, of which there are five. These all bear 

 a strong resemblance to the garden-snail, in 

 the formation of their shell, in their herma- 

 phrodite natures, in the slimy substance with 

 which they are covered, in the formation of 

 their intestines, and the disposition of the hole 

 on the right side of the neck, which serves at 

 once for the discharge of the feces, for the 

 lodging the instruments of generation, and for 

 respiration, when the animal is under a ne- 

 cessity of taking in a new supply. 



But, in nature, no two kinds of animals, 

 however like each other in figure or conforma- 

 tion, are of manners entirely the same. Though 

 the common garden-snail bears a very strong 

 resemblance to that of fresh-water, and that 

 of the sea, yet there are differences to be 

 found, and those very considerable ones. 



If we compare them with the fresh-water 

 mail, though we shall find a general resem- 

 blance, yet there are one or two remarkable 

 distinctions: and, first, the fresh- water snail, 

 and, as I should suppose, all snails that live 

 in water, are peculiarly furnished with a con- 

 trivance by Nature, for rising to the surface, 

 or sinking to the bottom. The manner in 

 which this is performed, is by opening and 



1 D'Argenville's Conchyliologie. 



shutting the orifice on the right side of the 

 neck, which is furnished with muscles for 

 that purpose. The "snail sometimes gathers 

 this aperture into an oblong tube, and stretches 

 or protends it above the surface of the wa- 

 ter, in order to draw in or expel the air, as it 

 finds occasion. This may not only be seen, 

 but heard also by the noise which the snail 

 makes in moving the water. By dilating this 

 it rises; by cdmpressing it the animal sinks 

 to the bottom. This is effected somewhat in 

 the manner in which little images of glass are 

 made to rise or sink in the water, by pressing 

 the air contained at the mouth of the tubes, so 

 that it shall drive the water into their hollow 

 bodies, which, before, were filled only with 

 air, and thus make them heavier than the ele- 

 ment in which they swim. In this manner 

 does the fresh water snail dive or swim, by 

 properly managing the air contained in its 

 body. 



But what renders these animals far more 

 worthy of notice is, that they are viviparous, 

 and bring forth their young not only alive, but 

 with their shells upon their backs. This 

 seems surprising ; yet it is incontestably true : 

 the young come to some degree of perfection 

 in the womb of the parent ; there they receive 

 their stony coat ; and from thence are exclu- 

 ded, with a complete apparatus for subsis- 

 tence. 



" On the twelfth of March," says Swam- 

 merdam, " I began my observations upon this 

 snail, and collected a great number of the 

 kind, which I put into a large basin filled 

 with rain-water, and fed, for a long time, with 

 potter's earth, dissolved in the water about 

 them. On the thirteenth of the same month 

 I opened one of these snails, when I found 

 nine living snails in its womb : the largest of 

 these were placed foremost, as the first candi- 

 dates for exclusion. I put them into fresh- 

 water, and they lived till the eighteenth of the 

 same month, moving and swimming, like 

 snails full grown : nay, their manner of swim- 

 ming was much more beautiful." Thus, at 

 whatever time of the year these snails are 

 opened they are found pregnant with eggs, or 

 with living snails ; or with both together. 



This striking difference between the fresh- 

 water and the garden snail, obtains also in 

 some of the sea kind: among which there are 

 some that are found viviparous, while others 

 lay eggs in the usual manner. Of "this kind 

 are one or two of the Buccinums ; within 

 which living young have been frequently found 

 upon their dissection. In general, however, 

 the rest of this numerous class bring forth 

 eggs; from whence the animal bursts at a 

 proper state of maturity, completely equipped 

 with a house, which the moistness of the ele- 

 ment where it resides does not prevent the in- 



