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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1860 Excerpt:...vertebrae are frequently subjected to the same kind of modification, either by way of excess or defect, and such groups of modified segments have received special names; such, for example, as " skull" (cranium), " neck" (cervix), "chest" (thorax), "pelvis," and "tail" (cauda); and these terms are reciprocally applied, when modified as adjectives, to the individual vertebrae so grouped together, and which are called " cranial vertebrae," "cervical vertebrae," "dorsal" or "thoracic vertebrae," "sacral" or "pelvic vertebrae," and "caudal vertebra." Skeleton of the Fish.--In all fishes the extent of ossification is less than in the higher vertebrate classes. Only in the skull do we find all the elements of the typical segment represented by bone. In the trunk, e. g., the haemapophyses and haemal spines never advance beyond the fibrous stage of tissue development. Four segments enter into the composition of the skull of fishes, answering to the first four in the archetype (Fig. 7), and they combine to constitute the bony framework of a head, burger in proportion to the trunk than in any other class of animals. The skull (Fig. 9), 3, 52, br, forms a cone, whose base is vertical, directed backwards, and joined to the trunk without an intervening neck, and whose sides are commonly three in SKELETON OF THE FISH. 173 number, one superior, and two lateral and inferior. The cone is shorter or longer, more or less compressed or squeezed from side to side, more or less depressed or flattened from above downwards, with a sharper or blunter apex, in different species of fishes. The base of the skull is perforated by the hole, called " foramen magnum,...