Horse-leeches are equally, if not more, abundant in ditches and stagnant waters, than the former species. They are so greedy of blood, that a vulgar notion is prevalent, that nine of them are able to destroy a horse. Medical men, in general, are cautious not to use them, from an opinion, though probably a groundless one, that their bite is noxious.

Molluscous Worms*.

OF THE SLUGS IN GENERAL†.

Few animals, for their size, are more voracious than these. They would do serious injury to our fields and gardens, were not their numbers abridged by several of the smaller quadrupeds, and by various species of birds.

They have so strong a tendency to reproduction, that, if the head or tail be cut off, these parts will grow again. Most of the species can exist for a great length of time, even for several months successively, without food.

* The Linnean order Mollusca consists of all those simple animals which are without shells, and are furnished with tentacula or arms. The greater number of them are inhabitants of the sea.

The body of the Slug is oblong, and has on its upper part a kind of fleshy shield; and, below, a flat, longitudinal disk, by means of which the animal has its progressive motion. On the right side of the body there is an aperture. Above the mouth are situated four tentacula, or feelers, at the apex of each of the two larger of which there is an eye.

THE SMALL GRAY SLUG*, AND BLACK SLUG †.

In moist gardens, meadows, fields, and woods, the former of these Slugs is but too common. Its time of going abroad in search of food is in the evening and night. During the day it lies concealed, either among the leaves of vegetables or under the surface of the ground. Its progress on the ground may easily be traced by the slime which it leaves in its track. Few animals are more destructive to vegetation than these.

These Slugs sometimes suspend themselves by a kind of thread, formed from the viscid substance which covers their bodies.

About the year 1789, in a plantation of Scotch firs, Mr. Hoy observed something suspended from one of the branches, which, as it seemed uncommon, he approached, and found to be a Slug. It was hanging, by a single line, or thread, attached to its tail. This, towards the upper part, was very fine; but near the animal it became thicker and more broad, till at length it exactly corresponded with the thickness of the tail. The Slug was about four feet below the branch, and nearly at the same distance from the ground; which it gradually approached at the rate of an inch in about three minutes.

The line by which it descended was drawn from the slimy exudation gradually secreted from the pores that covered its whole body. A great degree of exertion

DESCRIPTION. The usual length of this Slug is from half an inch to an inch. It is of a grayish white colour, with a yellowish shield. The tentacula are black.

SYNONYMS. Limax agrestis. Linnæus.-Spinning Limax. Linn. Tran.-Spinning Slug.-Limace agreste. Bosc.-La Petite Limace grise. Cuvier.

+ DESCRIPTION. This species is from one to three inches in length. Its body is black, furrowed, and wrinkled. The shield is whitish, and rough with numerous dots.

SYNONYMS. Limax ater. Linnæus.-Limace noire. Bosc. Cuvier.

seemed necessary to produce a sufficient supply of the liquid, and to force this toward the tail. It alternately pushed out and drew back its head; and turned it as far as possible, first to one side, and then to the other, as if thereby to press its sides, and thus promote the se cretion.

This is the substance of Mr. Hoy's account. Dr. Latham says that the secretion from which the thread is formed, is wholly from the under parts of the animal, and not from the back or sides, both of which, during the operation, appear nearly dry. That it did not proceed from any orifice in the tail was evident; for, in some experiments that were made, the animal suspended itself by the tip, and at other times from the side, a full eighth of an inch from the tip. The flow of the viscous secretion toward the tail appeared to be excited by means of an undulating motion of the belly, similar to that of crawling.

After having spun for some time, the power of spinning seemed for awhile to be lost; but in those Slugs on which experiments have been made, this power has always been recovered, by keeping them for some hours among wet moss.

The Black Slug, or Snail, is a well-known inhabitant of our fields and meadows, during the summer season. The country people consider the appearance of this Slug as an indication of approaching rain; but this is rather to be accounted for by the moisture of the ground and of the plants. It is seldom indeed to be observed abroad during dry weather, for this would deprive the external parts of its body of the moisture which is requisite for its subsistence. The Black Slug feeds on the roots and leaves of different kinds of plants.

OF THE APLYSIA TRIBE*.

The species of Aplysia, (or Laplysia, as, by a typographical error this tribe is named, in the Systema Naturæ,) are only three in number. One of them inhabits, the European seas, another the shores of Barbary, and the third the coasts of America.

These animals respire water by means of branchiæ, which form a kind of tuft on the back, and which are covered with an operculum or lid.

THE DEPILATORY APLYSIA †.

There is a general, though very unjust prejudice against this animal. Pliny and Dioscorides each speak in strong terms of its poisonous properties. "To some (says the former, by his translator, Philemon Holland) it is a very poison, if taken inwardly, either in meate or drink; to others again, the aspect and sight thereof is venomous. The same creature is hurtfull, even in the sea, if it be touched onely. Neither is there any living creature that feedeth upon this fish, but it dieth thereupon, unlesse it be the Sea Barbell onely; and all the harme that this fish catcheth by eating of it is this, that the flesh is the more tender. If a man or woman chance to be infected by eating of it, they presently smell and scent of the said fish: and this is the first sign and ar

The body is covered with reflected membranes. There is a shield-like membrane on the back; and in the right side an aperture. These animals have four feelers, which resemble

ears..

+ DESCRIPTION. The body of this animal, which is, apparently, a shapeless mass, enveloped in a loose skin, folding over and nearly meeting on the back, is from two to five inches in length, and of a pale lead-colour. The shield is circular, and on the middle of the back.

SYNONYMS. Laplysia dipilans.

Bosc.

Linn.-Laplésie depilante.

gument to prove that they be empoysoned thereby: howbeit, they die not immediately, but may continue so many daies as the said animal lived after it came out of the sea." It is generally supposed that the hair will fall off those parts of the body which are touched by these animals; and that they cause strangury to those who eat of them.

It is strange, observes Col. Montagu, that the poisonous touch and offensive smell which appear to have been the origin of the name of this Aplysia, should, without reason, have been handed down to posterity, and that a most unmerited opprobrium should so long have been fixed upon one of the most harmless and inoffensive of creatures. On the coast of Devon, this gentleman had frequent opportunity of handling these animals, which he invariably did with impunity: they neither affected the hand nor the olfactory nerves; but were found to be as destitute of smell as they are of any depilatory power.

Like the cuttle-fishes, they are furnished with a reservoir, which is filled with a dark-coloured fluid, and which they employ in concealing themselves from the attacks of their enemies. This fluid leaves a beautiful purple stain, and is discharged in such quantity, that it might possibly be turned to some advantage in dyeing, if a method could be devised to fix it.

They inhabit those parts of the sea, in the neighbourhood of rocks and sea-weeds, where the bottom is muddy. Their food consists chiefly of small crabs and shell-fish. They have three strong and muscular stomachs, with pyramidal bony processes, somewhat resembling those so well-known in the lobster.

OF THE AMPHITRITES IN GENERAL*. There is no tribe of marine animals that exceed these

The body of these animals is annulate, and projects from a tube. At its anterior extremity there are tentacula, which,