UNIVALVES.
Gasteropoda is a name given by some naturalists to a very extensive group of molluscous animals; the term is derived from two Greek words, signifying stomach and foot;—it has reference to the kind of fleshy foot which generally occupies the whole under side of the body, and by the contraction and extension of the muscles of which, the creature is enabled to glide, with a slow but steady motion, from place to place. The Slug and the Snail are the commonest examples which can be adduced of gasteropods; and one may tell by their slimy tracks, shining like silver in the morning sunshine, that during the night, which is their principal feeding time, they manage to get over a considerable extent of ground, although “a snail’s gallop” is a proverbial expression for slow motion; but it is astonishing how much work of any kind may be done if one “keeps at it;” by doing this the Tortoise beat the Hare, illustrating the truth of the proverb, that “slow and sure wins the race.” If you watch a Snail travelling with its house upon its back, it does not seem to make much way, and you are inclined to think that it will be long ere it reaches the new settlement to which it appears journeying with bag and baggage; but leave the spot for a while, and the chances are that on your return, the “slow coach” will have got somewhere out of sight. Here is a lesson for boys and girls; whatever you take in hand, don’t be in a hurry, and if people say you are “slow,” think of the snail, and keep on!
This, then, is a shelled mollusk of the third class, called Gasteropoda, according to the system of the French naturalist Cuvier. It has a distinct head, which, like the hinder part of the body, which we may call a tail if we like, projects, when the creature is in motion, considerably from the shell; it is also furnished with what we commonly call horns, naturalists say tentacles, from the Latin tento—trying, or essaying; with these the creature, as it were, feels its way; being extremely sensitive; they answer the purpose of organs both of sight and touch; put your finger slowly towards one of them, and you will observe that, even before contact, it begins to retract, or draw in, as though sensible of the approach of some opposing body, as it no doubt is. These horns of the snail, then, are its feelers—eyes to the blind, fingers to the fingerless; so God provides for his creatures all that may be necessary for their existence, and compensates for the deprivation of one sense or organ, by some admirable contrivance which meets the necessities of the case.[1]
[1] It appears likely that the little knobs at the end of the snail’s feelers, are, as some naturalists assert, in reality eyes; if so, we were wrong in calling the creature blind. Yet is their position and construction so different from organs of sight generally, that they serve rather to strengthen than invalidate the above observations. The number of the horns varies in different kinds of snails from two to six, and some have none at all. These tentacles, when present, are always situated above the mouth; some of them have the knobs at the base, others at the sides; and it has been conjectured that they may be organs of smell, as well as of sight and touch.