CHAPTER XVIII. THE NOTOCHORD, THE VERTEBRAL COLUMN, THE RIBS, AND THE

STERNUM. Pp. 542-563.

Introductory remarks on the origin of the skeleton, pp. 542-544. Bibliography of the origin of the skeleton, pp. 544, 545. The notochord and its cartilaginous sheath, pp. 545-549. _The vertebral arches and the vertebral bodies_, pp. 549-559. Cyclostomata, p. 549. Elasmobranchii, pp. 549-553. Ganoidei, p. 553. Teleostei, p. 553. Amphibia, pp. 553-556. Reptilia, pp. 556, 557. Aves, pp. 557, 558. Mammalia, pp. 558, 559. Bibliography of the notochord and vertebral column, p. 560. _Ribs_, pp. 560-562. _Sternum_, pp. 562, 563. Bibliography of the ribs and sternum, p. 563.