CHAPTER IV.

THE SKELETON OF THE FISH.

Specialization of the Skeleton.--Homologies of Bones of Fishes.--Parts of the Skeleton.--Names of Bones of Fishes.--Bones of the Cranium.--Bones of the Jaws.--The Suspensorium of the Mandible.--Membrane Bones of Head.--Branchial Bones.--The Gill-arches.--The Pharyngeals.--The Vertebral Column.--The Interneurals and Interhæmals.--The Pectoral Limb.--The Shoulder-girdle.--The Posterior Limb.--Degeneration.--The Skeleton in Primitive Fishes.--The Skeleton of Sharks.--The Archipterygium. 34