Book Description

Excerpt from The Mollusca and Radiata: Arranged by the Baron Cuvier, With Supplementary Additions to Each Order The mollusca have neither an articulated skeleton, nor a vertebral canal. Their nervous system is not united in a spinal marrow, but merely in a certain number of medullary masses, dispersed in different parts of the body, the chief of which, termed the brain, is situated transversely on the sophagus, and envelopes it with a nervous collar. Their organs of motion and sensation have not the same uniformity of number and position as in the vertebrata, and the irregularity is still more striking in the viscera, particularly as respects the position of the heart and respiratory organs, and even as regards the structure of the latter; for some of these respire elastic air, and others salt or fresh water. Their external organs, however, and those of locomotion, are generally arranged symmetrically on the two sides of an axis. The circulation of the mollusca is always double; that is, their pulmonary circulation describes a separate and distinct circle. This function is at least always aided by a fleshy ventricle, situated between the veins of the lungs and the arteries of the body, and not, as in fishes, between the veins of the body and the arteries of the lungs. It is then an aortic ventricle. The cephalopoda alone are provided with a pulmonary ventricle, which is even divided into two. 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."