. The Cambridge natural history. Zoology. 14 URODELA. Fig. 2.—Transverse section through a truuk - vertebra of a larva of Salo- mandra maculosa, enlarged. The right side shows the actually existing state, while on the left side the rib and its attachments are restored to their pro- bable original condition. A, Verte- bral artery within the true transverse canal ; B. V, remnant of the basi-ventral All the trunk-vertebrae, with the exception of the atlas, carry ribs, at least vestiges thereof. Owing to the early dis- appearance of the basiventral cartilages the capitular portions of the ribs are
. The Cambridge natural history. Zoology. 14 URODELA. Fig. 2.—Transverse section through a truuk - vertebra of a larva of Salo- mandra maculosa, enlarged. The right side shows the actually existing state, while on the left side the rib and its attachments are restored to their pro- bable original condition. A, Verte- bral artery within the true transverse canal ; B. V, remnant of the basi-ventral All the trunk-vertebrae, with the exception of the atlas, carry ribs, at least vestiges thereof. Owing to the early dis- appearance of the basiventral cartilages the capitular portions of the ribs are much reduced, and are mostly represented l»y strands of connective tissue only. The ribs develop therefore occasion- ally at some distance from the vertebral column, and that por- tion of the rib which in the metamorphosed young newt looks like the capitulum is to a great extent really its tuberculum. Witness the position of the ver- tebral artery, which still indi- cates the true foramen trans- versariura. The homologies of these parts are still more ob- scured by the fact that a new cartilage; Ck, chorda dorsalis; , procCSS growS OUt from the rib, spinal caual; *, the false transverse , i • i ^ i i , , canal. by which the latter gams a new support upon a knob of the neural arch. Thus an additional foramen is formed, sometimes confounded with the true transverse canal. The meaning which underlies all these modifications is the broadening of the body, the ribs shifting their originally more ventral support towards the dorsal side. The whole process is intensified in the Anura; it is an initial stage of the notocentrous type of vertebrae. The transverse ossified processes of the adult are often much longer than the vestiges of the ribs themselves, and are somewhat com- plicated structures. Tiiey are composed first of the rib-bearing cartilaginous outgrowths of the neural arches ; secondly, of a broad string of connective tissue which extends from the ventro-lateral cor
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
