Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/498

 SNA

SNA

wnite fpots, and with the edge of the back fin black. See the article Murjena.

SMYTHAM, in mineralogy, lead-ore Stamped and pounded down, like powder or Sand, to cleanfe the Stones and earth from the ore. Houghton's Compl. Miner in the Explan. of the Terms.

SNAFFLE, in the manege, a well known kind of bridle. The fnaffle, after the Englifh fafhion, is a very flender bit-mouth without any branches : they are much ufed in England in- stead of true bridles, which are only employed in the fervice of war. The French call them bridons % by way of distinc- tion from brides, i. e. bridles.

The fnaffle, or fmall watering-bit, is commonly a fcatch- mouth, accoutred with two little very Straight branches, and a curb, and mounted with a head-flail and two long reins of Hungary leather.

SNAIL, in ichthyography. See Liparis noflras.

Perrauk doubts of fnails having eyes, and Dr. Brown denies it; but according to Dr. Porterfield, a good micro- fcope ihews them diftinctly. Med. Eft. Edinb. Vol. 3. Art. 12.

The eyes of fnaih are lodged in their four horns, one at the end of each horn, which they can retract at pleafure. Id ibid.

The manner of examining thefe eyes is this : when the horns are out, cut off nimbly the extremity of one of them, and placing it before the microfcope, you may difcover the black fpot at the end to be really a femiglobular eye. The diflection of this animal is very curious ; for by thi means, the microfcope not only difcovers the heart beating jiift againft the round hole near the neck, which feems the place of refpiration, but alfo the liver, fpleen, Stomach, and interlines, with the veins, arteries, mouth, and teeth, are plainly obfervable. The guts of this creature are green from its eating of herbs, and are branched all over with fine capillary white veins. The mouth is like a hare's, or rabbet's, with four or fix needle-teeth, refembling thofe of leeches, and of a fubftance like horn. Snails are all hermaphrodites, having all each fex united in the individual ; they lay their eggs with great care in the earth, and the young ones are hatched with ihells compleatly formed. Cutting off a fnaifs head, a little Stone appears, which is fuppofed to be a great diuretic, and good in all ne- phritic diforders. Immediately under this ftone the heart is feen beating, and the auricles are evidently diftin- guifhable, and are membranous, and of a white colour ; as are alfo the veffels which proceed from them. Snails difchargc their excrements at a hole in their neck ; they alfo breathe by this hole, and their parts of generation are fituated very near it. The penis is very long, and in fhape refembles that of a whale. Baker's Microfcope, p. 217.

So fmall an animal as the fnail is not free from the plague of fupporting other fmaller animals on its body; and as in other animals we find thefe fecondary ones either living only on their furface, as lice, &c. or only in the interlines, as worms, it is very remarkable that this creature infefts the fnail in both thefe manners, being found fometimes on the furface of its body, and fometimes within its inteftines. There is a part of the common garden -fnail, and of other of the like kinds, commonly called the collar ; this furrounds the neck of the fnail, and is confiderably thick, and is the only part that is vifible, when the animal is retired quietly into its fhell. In this ftate of the animal thefe infects, which infeft it, are ufually feen in confiderable numbers marching about very nimbly on this part : this nimble motion is al- moft peculiar to then), mod other creatures of this kind be- ing very flow in their motions : they may be feen in many other circumftances of the animal, but it is this in which they are moft obvious to the naked eye. Though they are very fmall, they cannot however make their way under the fhell, to run over the reft of the body of the fnail, every part of it adheres too firmly to the fhell to fufrer that ; but they have another very different way of enlarging their place of abode : the fnail, every time it has occafion to open its anus, gives them a place by which to enter into its inteftines, and they often feize the opportunity. The anus of this creature is fituated not within the fhell, but in this collar, which furrounds the mouth of it; and the fnail fcldom moves, to go a little way out of its fhell, without opening it, as it does alfo in many other circumftances. Thefe infects always take advantage of the opening, and fwiftly get in and run up into the inteftines, infomuch that their natural refidence feems there, and that they never are upon the furface of the animal but by accident, and much againft their will ; they feem to be driven thither by this ac- cident: the faeces of the fnail fill up the whole width of the inteftine, and when they are difcharged, muft necefiarily carry out with them whatever is between them and the anus ; now it may eafily happen, that a number of thefe fmall animals may be in that part of the inteftine, which is between the anus and the feces : all thefe muft be dif- charged with them, and while they are walking about upon the neck of the animal, the aperture of the anus clofes,

and leaves them no power of entering back again, till an- other opportunity ; and the frequency of this accident may eafily drive out enough of thefe infects, to keep always f om J upon the neck, though every one of them, while there, i s fceking the firft opportunity of getting into the inteftines again.

Thefe infects infeft every kind of fnail, though they are moft frequent on the common large garden-kind ; but there is a fmall Species of fnail, remarkable for a "fort of cover nearly as hard as the fhell, with which the creature clofes up its mouth upon occafion : in this thefe creatures may be diftinguifhed, even within the inteftines. The fkin of this fnail is very thin and tranfparenf; and if the fhell be broken oft" a little way, and the eye kept attentively on that part, thefe little infects will be diftinguifhed through the fkin run- ning nimbly about in the inteftines.

Though thefe infects are found in all forts of fnails, they are not to be feen at all times ; rainy feafons feem parti- cularly disadvantageous to' them, and it is only in dry times that they are always to be.fuund when looked for ; whether it be that the rain deftroys the animals, when already form- ed, or that they are in themfelves but Short-lived, and the rain prevents the hatching of the eggs for more. The in- fects are content with the naked body of the fnail alone as their habitation, they never get upon the fhell, and if they are forced to it, they as foon as poffible quit it again, and get to their old poft. They appear of a whitifh colour to the naked eye, fome of a dirty greyifh white, and fome of a white with a mixture of reddifhnefs ; but a microfcope is neceffary to give us a view of their different parts and Struc- ture. They have a regular trunk, in the manner of many other infects, which they occafionally can bend downwards, and in a great meafure hide from the fight : this trunk, which ferves them to fuck in their nourishment from the body of the fnail, is placed between two little horns, which are extremely moveable every way, and are capable of be- ing extended in length, or fliortened, in the manner of the horns of the fnail, which is a circurnftance not obfervable in the horns, or antennae of other infects. The body is di- vided into fix rings, befide the anterior part, on which are placed the horns and the trunk. The creature has four legs on each fide, two of which on each are articulated into the anterior part, which gives rife to the horns and trunk, and the other two into the firft ring of the body ; fo that they ftand in pairs, the fecond and third on each fide being greatly more diftant from one another than the firft and fecond, or the third and fourth : thefe legs are all furnifhed with very long hairs, and feem to terminate, each in two or three points, in the manner of the legs of many of the beetles. The back is elevated into a convex form, the fides alfo are rounded, and each ornamented with three or four hairs ; but there are none under the belly. Mem. Acad. Par. 171 1.

Snails are great deftroyers of fruit in our gardens, efpecially to the bitter forts of wall-fruit. Lime and afhes Sprinkled on the ground where they moft refort, will drive them away, and deftroy the young brood of them. It is a common prac- tice to pull off the fruit they have bitten, but this fhould never be done, for they will eat no other till they have wholly eat up this, if it be left for them. The Romans were fond of fnaih, and had them fed on pur- pofe for their tables. Their tafte is not delicious, but rather difagrceable ; but this they difguifed by means of good fauces, and had other reafons for the receiving them into the lift of foods. They ufed them as provocatives, or inciters to venery, and with this intent they eat only the necks, as the part in which the parts of generation of the creature were placed ; and :hey had the greater opinion of the efficacy of thefe, as the parts of generation were double in each indi- vidual, that is, the male and female parts both fituated in the neck of every fnail.

Ariftotle, and the old Greeks, had no idea of the generation of thefe infects, in the manner of other animals, but fup- pofed them produced fpontaneoufly ; but the Romans Shew, by many paffages in their writings, that they had got over this error, and even feem, by the preference they gave to the neck of this animal, in this intention to have underftood the hermaphrodite Structure of this infect, which much later ages have pretended to make a new difcovery. The Eaftern nations at prefent run much into the opinions of the Romans of old, as to provocatives ; they ufe, as the others did, every thing that ferves to the purpofes of gene- ration in other animals, and every thing that has but the refemblance of the external figure of the parts fubfervient to it. The orchis roots, which refemble the tefticles of ani- mals in fhape, and contain a white and Slimy, or vifcous liquor, have introduced themfelves into ufe on this plan, and fo of many other things. Phil. Tranf. N° 50. O^i-Snail, a name given by Dr. Lifter, in the Philofophical Transactions, to a fmall fnail, which he obferved under the loofe bark of old willows, elms, and others trees, and which is of a very fingular Structure; the fhell refembling an oat- corn, whence the name, and its volutce, or wreaths, run- ning contrary to the direction of them in other fnails, that