630 DEPTHS OF THE OCEAN 



limit at about 500 metres, where they are found together with 

 the upper representatives of the bathypelagic fauna, just as on 

 the continental slopes the Macrurid bottom-fauna is mingled 

 with the deepest living species belonging to the coast banks. 

 Fig. 478 shows the vertical distribution of certain of these 

 pelagic fishes, and we see that Sternoptyx diaphana, Stomias 

 boa, and Chauliodus sloanei were taken most abundantly at 

 500 metres, while the species of the genera Argyropelectis, 

 Valenciennellus, and Vinciguerria were mostly taken at 300 

 metres ; the upper limit for all these species seems to be about 

 150 metres below the surface. As regards the geographical 

 distribution of these species, we find that, excepting Stomias boa, 

 they occur in the Indian Ocean to the north of lat. 40° S., and in 

 the Atlantic between lat. 44^ N. and 40° S., though Argyropelecus 

 olfersi, A. actileatus, and A. kei7iigymnus have been found on 

 the coasts of Norway, and Stomias boa has been taken in 

 the Faroe-Shetland channel during one of our cruises in the 

 " Michael Sars." 



During our Atlantic cruise in 19 10, Argyropelecus affinis 

 and A. actileatus, Valenciemielhis tripunctiilatus, IchthyococciLS 

 ovatuSy and Serrivomer sector were only taken at our southern 

 stations, and did not appear at any of the stations between 

 Newfoundland and Ireland, while Argyropelecus hemigymnus, 

 Sternoptyx diapha^ia, Stomias boa, and Chauliodus sloanei were 

 caught both at northern and southern stations, but only Stomias 

 boa occurred in numbers of any consequence at the northern 

 stations. Thus, of 286 specimens oi Argyropelecus hemigymnus 

 taken during the cruise only 1 7 were captured on our northern 

 track; of loi specimens of Sternoptyx diaphana only 2 were 

 taken north of the Azores ; of 95 specimens of Chauliodus 

 sloanei ow\y 10 were taken north of the Azores. On the other 

 hand, out of our total of 154 specimens of Sto7nias boa 91 were 

 taken on the northern track, and this species appears to be 

 the only abundant one north of lat. 45" N. 



The temperature throughout the region occupied by these 

 fishes, between lat. 40^ S. and 45° N., and between 500 

 and 150 metres, exceeds 10° C. We found the distribution 

 of the fishes of the Atlantic coast banks to be limited by this 

 temperature in a northerly direction as well as vertically. A 

 limit of this kind can only be roughly fixed, and is subject to 

 variations, but the isotherm of 10" C. seems on the whole to 

 coincide with the localities where the organisms in question 

 occur in numbers of importance. Within the region great 



