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A TEXTBOOK OF OCEANOGRAPHY 



belonging to the family Macruridae and 8 Zoarcidœ, as being 

 certainly captured on the abyssal plain. 



This is the total resuit of ail attempts to capture bottom 

 fish beyond the 2,000-fathom line. This scarcity of fish is 

 associated with a scarcity of other forms of life. In the 

 Challenger reports large numbers of species of invertebrates 

 are known only from a single locality, and often from one 

 spécimen only. The abyssal fish hâve a wide distribution, 

 both horizontal — i.e., they are found at places wide apart 

 in the différent océans — and vertical — i.e., they occur on the 

 continental slopes as well as on the abyssal plain. 



FiG. 4. — Abyssal Fish (Macrurus). 



FiG. 4A. — Abyssal Fish (Lycodes) 



Sir John Murray has summarised the results of the deep- 

 sea trawling and dredging of the Challenger expédition. At 

 25 stations where the depth exceeded 2,500 fathoms 600 indi- 

 vidual animais were captured; this gives 24 individuals per 

 haul. Many of thèse, however, are undoubtedly pelagic — 

 certainly most of the crustacea and some of the fish. 



Some of the other organisms were very small — e.g., 

 hydrozoa and bryozoa. It is certain that animal life is very 

 poorly developed on the abyssal plain. 



The Norwegian fisheries' investigation steamer Michacl 

 Sars has made three successful hauls at depths of over 2,500 



