Book Description

Excerpt from The Class Pisces Suspended in a fluid nearly as heavy as themselves, the former have no need of wings to sustain them in it. A great number of species have immediately under the spine an air vessel, which by compression or dilatation changes the specific gravity of the fish, and assists it in rising or descending in the water. Progression is executed by the motion of the tail, which strikes the water alternately right and left, and forces the fish forward; the gills discharging the water backward probably contribute also thereto. Hence, the limbs being but of little use are greatly reduced; the pieces analogous to the bones of the arms and of the legs are extremely short or entirely concealed; rays more or less numerous, supporting membranaceous fins in some degree represent fingers and toes. The fins corresponding to the anterior extremities are said to be pectoral, those which answer to the posterior are said to be ventral. Other rays attached to particular bones placed upon or between the extremities of the spinous processes support vertical fins on the back, under the tail, and at its extremity, which by being erected or depressed, extend or diminish at the will of the fish, the surface which strikes the water. The upper fins are said to be dorsal, the lower anal, and that of the end of the tail caudal. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.