CHAPTER III. The Evidence of the Skeleton

THE EVIDENCE OF THE SKELETON

The bony and cartilaginous skeleton considered, not the notochord-- Nature of the earliest cartilaginous skeleton--The mesosomatic skeleton of Ammocoetes; its topographical arrangement, its structure, its origin in muco-cartilage--The prosomatic skeleton of Ammocoetes; the trabeculæ and parachordals, their structure, their origin in white fibrous tissue--The mesosomatic skeleton of Limulus compared with that of Ammocoetes; similarity of position, of structure, of origin in muco-cartilage--The prosomatic skeleton of Limulus; the entosternite, or plastron, compared with the trabeculæ of Ammocoetes; similarity of position, of structure, of origin in fibrous tissue--Summary 119