THE COD FAMILY 95 



V. The pollack. — Like the preceding but with no barbel and 

 the lower jaw longer. Colour a dark green. 



II. Species with two dorsal fins, the hinder long, the front one 

 short ; one ventral fin : 



vi. The ling. — A barbel on the chin. Body elongated, scales 



minute, fins narrow, very flexible, 

 vii. The Mediterranean ling. — Molva elongata, more elongate, 



and more eel-like than the common ling, molva vulgaris, 

 viii. The burbot. — Closely resembles the ling, but the body is 



broader behind, the head and the scales are larger and the 



fish is much smaller. 

 ix. The fork-beard. — A barbel on the chin. The pelvic fin 



forms a long filament extending behind the vent. 



III. Species in which there is no separate first dorsal, but the 

 front of the single dorsal is a narrow fringe kept vibrating dming 

 Hfe: 



X. The three-bearded rockling, 

 xi. The five-bearded rockling. 



MERLUCCIIDAE 



The hake. — This has been omitted from Cunningham's classi- 

 fication, as although it is in many ways like a gadoid, several features 

 have made it clear that it belongs to a separate genus. Its external 

 features are, no barbel, scales larger than the ling, fins broader and 

 stifEer. Teeth larger and mouth black. 



When we attempt to study the relationship of feeding-habits 

 to the brain pattern in the cod family, we find some different 

 features from those we have described in the Cyprinoids. In the 

 latter family we w^ere able to describe three groups, each with its 

 characteristic brain pattern, and the third group could be further 

 sub-divided into two sub-groups. In the cods or gadidse we shall 

 find that the different species can be graded into a greater number 

 of groups, and that in the first of these groups further sub-divisions 

 can be made according to their diet, whether this is mostly of Crus- 

 tacea and shell-fish, or is mostly fish ; between these two extremes 

 we find intermediate types, for example, a diet largely of Crustacea 

 but also fish or a diet mostly fish, but occasionally Crustacea. When 

 we examine the pattern of the medulla oblongata we find a gradation 

 corresponding to the types which vary between the two extremes. 



Some authorities have been unable to identify the facial Jobe in 

 the cod family. We have made a detailed study of the brain of 

 the whiting and have clearly established its existence ; in those 



