There are five branchial arches, the first four of which bear gill rays. Each of the first three consists of a shorter upper portion directed obliquely backwards and outwards, and a longer lower portion forming a right angle with the upper and directed obliquely forwards and inwards. The greater part of each arch is ossified. The upper part of either of the first two consists of a short tapering =pharyngo-branchial= directed inwards, and of a long =epi-branchial= tipped with cartilage at both ends. The junction of the upper and lower parts is formed by a cartilaginous hinge-joint between the epi-branchial and cerato-branchial. The =cerato-branchial= is a long bony rod separated by a short area of cartilage from the =hypo-branchial=, which is succeeded by the =basibranchial= meeting its fellow in the middle line. The =fourth arch= has a short epi-branchial and no ossified pharyngo-branchial, while the fifth is reduced to little more than the cerato-branchial, which bears a few teeth on its inner edge. All the branchial arches have projecting from their surfaces a number of little processes which act as strainers. The first and fourth arches have one series of these, the second and third have two. THE SKULL OF THE CODFISH[37]. A full description having been already given of the Salmon's skull, that of the Codfish will be described in a briefer manner. The skull is very fully ossified, and the great number of plate-like bones render it a very complicated structure. THE CRANIUM. At the posterior end of the dorsal surface is the large =supra-occipital=, which is drawn out behind into the large blade-like =occipital spine=. On each side of the supra-occipital are the small irregular _parietals_, while in front of it the roof of the skull is mainly formed by the very large unpaired _frontal_.