Download The Kingdoms of Nature, Or, Life and Organization from the Elements to Man Book in PDF, ePub and Kindle
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1884 edition. Excerpt: ...to the function they perform. From each segment, ventrally, the arched processes form the jaws, ribs, and pelvis, inclosing the organs of nutrition and reproduction. The locomotive extremities are in two pairs, the similarity in the bones of which may be traced from the fish to man, though in the former in a rudimentary condition. 1. All are oviparous. 2. Breathe by gills, or branchiaa. 3. All have cold red blood. 4. Heart consists of two cavities, with the exception of the first order, which has but one. 5. Body adapted to swimming, tapering each way from the middle, covered with scales. Have a head, but no neck or loins. Tail adapted, oar-like, to aqueous locomotion. Dorsal and ventral fins, when present, used for balancing. Limbs rudimentary. 6. jaws move. vertically. In considering the structure (anatomy) of fishes, the lowest class of the vertebrate sub-kingdom of animals, it is thought best to take as an example one of the bony fishes, as the common codtish or trout, and examine its THE JOHN CRERAR LIBRARY. VERTEBRATE SEGMENTATION. 265 structure; after which the variations in the different orders may be considered. The skeleton of this class may be either cartilaginous or bony. By far the greater number are bony. 'The order Selachii have all a cartilaginous skeleton, while that of some others is partly osseous and partly cartilaginous. The bones of the Teleostean fishes are more fibrous, and consequently more elastic than those of the higher classes, as birds and mammals. The skeleton of a fish is divided into skull, trunk, and limbs. The skull and face-bones are supposed to consist of a very materially modified condition of four vertebral segments and their dorsal and ventral appendages. The segments are named as follows: ...