. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 500. Cartilaginous skull and anterior portion of vertebral column of the Sturgeon (Accipenser sturio). a, cartilaginous axis of spine ; b, c, transverse apophyses and ribs ; f,f, g, g', g", g", g"", cartilaginous cranium; i, k, ocular and nasal cranial cavities ; m, n, pedicle by which the mouth is connected with the cranium; 26, bone supporting the lower jaw ; 18,22, palatine cartilages; o,p,s, cartilages representing the superior maxilla. were only a moiety of the posterior division of the fin of th
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 500. Cartilaginous skull and anterior portion of vertebral column of the Sturgeon (Accipenser sturio). a, cartilaginous axis of spine ; b, c, transverse apophyses and ribs ; f,f, g, g', g", g", g"", cartilaginous cranium; i, k, ocular and nasal cranial cavities ; m, n, pedicle by which the mouth is connected with the cranium; 26, bone supporting the lower jaw ; 18,22, palatine cartilages; o,p,s, cartilages representing the superior maxilla. were only a moiety of the posterior division of the fin of the preceding genus. The posterior extremities or ventral fins are attached to a zone similar to that which supports the pectorals (Jig. 500,14). The pelvic zone is, however, very incomplete, the superior or iliac portion being quite deficient, so that it has no connection with the spine, but is simply im- bedded among the muscles at the posterior part of the abdomen. Externally the pelvis supports the first ray of the ventral fin (jig. 500, 15), which is very large, and likewise a long stem (16) composed of nume- rous articulations, to the commence- ment of which the succeeding fin rays are appended. Inferiorly the former is prolonged in the male Rays into a very curious club- shaped apparatus called the "clasp- er," of the nature of which we shall have occasion to speak further on. Skeleton of Dermapterygii.—In the cyclostomatous Fishes, such as the Lamprey, the skeleton is of still more simple structure than in the plagiostomatous genera. The cranium exhibits through life a soft carti- laginous texture; nevertheless it is not difficult to identify the different pieces of which it con- sists, and to point out their analogies with those of the osseous Fishes. The spine consists of a soft cartilaginous stem, which passes along the entire length of the body. It is enclosed in a strong membra- nous investment, from which prolongations are given off that perform the off
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