Elements of comparative anatomy (1878) Elements of comparative anatomy elementsofcompar00gege Year: 1878 Reptilia and Aves ribs are found along the whole of the dorsal portion of the vertebral column, and are absent only in the Chelonii. The movable cervical ribs of the Reptilia unite with the vertebra) in the Aves (Fig. 226, co), and the two together bound a foramen trans versarium. In the caudal region of the column of the Saurii, Chelonii, and Crocodilini we meet with inferior arches, which are always attached be- tween two centra, and take part in the forma- tion of a caudal canal. They a
Elements of comparative anatomy (1878) Elements of comparative anatomy elementsofcompar00gege Year: 1878 Reptilia and Aves ribs are found along the whole of the dorsal portion of the vertebral column, and are absent only in the Chelonii. The movable cervical ribs of the Reptilia unite with the vertebra) in the Aves (Fig. 226, co), and the two together bound a foramen trans versarium. In the caudal region of the column of the Saurii, Chelonii, and Crocodilini we meet with inferior arches, which are always attached be- tween two centra, and take part in the forma- tion of a caudal canal. They are rudimentary in Birds. The inferior processes of the Ophidii, Saurii, and Aves, which are given off directly from the centra, are quite different from these. On comparing the vertebral column of the Reptilia and Aves with that of the Amphibia we can see that it is divided into a larger number of regions. A cervical and a lumbar region are more distinctly marked off, owing to the connection between a number of ribs and a sternum. The lumbar region con- tains the pre-sacral group of vertebra?, which have only short ribs; it is dis- tinct in the Saurii and Crocodilini. The absence of any sternal connections in the Ophidii is the cause of there being no difference between the tho- racic and cervical regions in these forms, as well as of the impossibility of distinguishing a lumbar one. In the Chelonii also the vertebras of the trunk are similar in character through- out. These regions are not, however, very sharply marked off from one another, inasmuch as in the Saurii Fig. 227. Sacral por- Fig. 228. Sacral portion of tion of the vertebral the vertebral column of a bird. column of a Reptile, with the adjacent pre- and post-sacral vertebra). Both of these diagrammatic figures are drawn as if from the ventral surface, and show the nervous plexus on the left. In both the figures a is the first sacral vertebra, b the second sacral vertebra. . . . 1, 2, 3,4 Presacral. 1', 2',3',4' ...
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