CHAPTER VII.
THE SKELETON OF THE CODFISH.[35] (Gadus morrhua.)
I. EXOSKELETON.
The exoskeleton includes
(1) Scales. These are of the type known as cycloid and consist of flat rounded plates composed of concentrically arranged laminae of calcified matter, with the posterior margin entire. The anterior end of each scale is imbedded in the skin and is overlapped by the preceding scales.
(2) The teeth. These are small, pointed, calcified structures arranged in large groups on the premaxillae, mandible, vomer, and superior and inferior pharyngeal bones.
(3) The fin-rays. These are delicate, nearly straight bony rods which support the fins.
II. ENDOSKELETON.
The endoskeleton of the Codfish, though partially cartilaginous, is mainly ossified.
It is divisible into an axial portion, including the skull, vertebral column, ribs, and skeleton of the median fins, and an appendicular portion, including the skeleton of the paired fins and their girdles.