96 THE VEHTEBRATE SKELETON. 



in the middle line. The fourth arch has a short epi-branchial 

 and no ossified pharyn go-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 pro- 

 jecting 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 1 . 



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-occi- 

 pital are the small irregular parietals, while in front of it the 

 roof of the skull is mainly formed by the very large unpaired 

 frontal. 



A complicated series of bones are developed in connection 

 with the auditory capsule, which forms a large projecting 

 mass united with the side of the cranium and drawn out be- 

 hind into a pair of strong processes, the epi-otic and parotic 

 processes. Both these processes are connected behind with a 

 large Y-shaped bone, the post-temporal (fig. 13, 1), which will 

 be described when dealing with the pectoral girdle. The epi- 

 otic process is formed by the epi-otic, which is continuous in 

 front with the parietal. The parotic process is formed by 

 two larger bones, a more dorsal one, the pterotic, and a more 

 ventral and internal one, the opisthotic, which is continuous 

 in front with the large pro-otic. Intervening between the 



1 T. J. Parker, Zootomy, London, 1884, p. 91. 



