The Spinous Sea-Mouse, or Sea-Caterpillar,
([Halithæa aculeata].)
The Sea-Mouse is found in the European seas, and when in its native element is singularly beautiful, the hair with which it is partially covered being equal in splendour to the colours on the tail of a peacock.
Halithæa aculeata.
ORDER ANNULATA APODA,
(Footless Annulose Animals.)
The greater portion of the Annulose animals, namely those already described, are furnished with small projecting points on the sides of their body, which assist them in their motions, and which may, consequently, be considered as supplying the place of feet; but those we have yet to notice have no similar appendages, and, therefore, they are called footless. They are all very lively in their movements, and live either in moist earth, or the mud at the bottom of ponds. We find among the footless Annulata two well-known genera, namely, the Earth-worm and the Leech.
The Common Earth-Worm,
(Lumbricus terrestris.)
The body of the Earth-worm is composed of a great number of narrow rings, and along each side are four rows of very small, short, silk-like bristles, of a substance partly horny and partly shell-like. These bristles are placed on the edges of the rings, and it is by the alternate contraction and expansion of these rings that the worm is enabled to move along, the little bristles acting like hooks, and so forming various fixed points of resistance or fulcra, upon which the animal can rest at each movement forwards. The organization of the Earth-worm is very simple, the intestinal canal for the food being a simple straight tube, except in one part of its length, where a kind of gizzard is found, which answers the purpose of a stomach. It is supposed to feed upon the vegetable substances it finds in the earth.
