Elements of Natural History, Vol. 2

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Excerpt from Elements of Natural History, Vol. 2: Adapted to the Present State of the Science, Containing the Generic Characters of Nearly the Whole Animal Kingdom, and the Descriptions of the Principal Species The animal destitute a vertebral column and bony skeleton form the second and by far the most numerous group of living beings. In the system of Linnaeus the Invertebral Animals were included in two great classes, Insecta and Vermes, but subsequent investigations into their nature and organization have given rise to more numerous and better characterized groups. Possessing little analogy in point of structure with the vertebral animals, some are found with the body unprotected, except by a soft skin, others are covered by a shell, while others have their members enveloped in crustaceous plates. The circulating system in this division is also less perfect than in the vertebral animals, and, with the exception of a few groups, none have red blood. The nervous system appears also in a less complete form, and, instead of the medullary mass of the brain and spinal chord of the higher classes, they present only ganglions or knots in the nervous threads. No class of invertebral animals possesses all the organs of sense, for while some are destitute of the organs of hearing, others seem deprived of the faculty of smell and sight, and many appear to be guided only by the sense of touch. The sexes, besides, are in many groups united in the same individuals, and in others the species is continued by a process analogous to the budding of vegetables. 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.