390 DEPTHS OF THE OCEAN 



of the coast-banks, and the genera Mora, Lepidion, and Halargyreiis the 

 uppermost part of the continental slope. 



The Acanthopterygii.- — Fifty-one species belong to this very important 

 and large group of highly developed fishes, most of which are true coast- 

 bank fishes, only a few of them being known from the uppermost part 

 of the slope. 



Most of these fishes, the Serranidae, Sciaenidae, Pristipomatids, 

 Sparidae, Mullidae, Caproidae, Labridae, Scorpaenidae, Triglidae, Trachi- 

 nidai, Uranoscopidae, and Callionymidae, are brightly-coloured fishes, with 

 hard ossified scales and spines of moderate size, living in shallow water, 

 or deeper, on the coast-banks, with a maximum distribution in warm 

 subtropical waters. The northern limit of their distribution differs for 

 different species, several extending even to the southern warmer parts of 

 the bays and fjords of Scandinavia; other families, e.g. Cottidae and 

 Blenniidae, have representatives in the Arctic {Triglops, Lumpenus). 

 None of these families have, however, any economical importance in 

 the Norwegian Sea or North Sea. 



The family Pleuronectidae, or flounders, includes very important 

 food-fishes. The plaice, flounder, sole, dab, megrim, halibut, all belong 

 to this family. Hippoglossus, Pleuronectes, and Zeugopterus are northern 

 genera ; Solea is the most important genus in the Atlantic, Solea 

 vulgaris being of importance also in the southern parts of the North Sea. 



The Scombriformes, to which belong the genera Trachurus or 

 Caranx, Scomber, Thynnus, are mostly pelagic, but are also caught very 

 near to the shore. The mackerel, the tunny, the horse-mackerel are 

 all economic species of great importance. 



Class— PISCES 



Sub-Olass— ELASMOBRANOHII 



Order — PL AGIOSTOMI 

 Sub-Order— SELACHII 



NOTIDANID^ 



Notidanus griseus, Cuv. (six-gilled shark), 1902, Faroe-Shetland channel (Fig. 

 253)- 



Fig. 253. 

 Notidanus griseus, Cuv. (After Bonaparte.) 



