420 DEPTHS OF THE OCEAN 



the methods of capture, the technical difficulties of operating 

 dredges and trawls at great depths being of considerable 

 moment, but I do not attach great importance to this, because 

 the same appliances, when used in deep water on the continental 

 slope, gave large catches. 



If we fix the boundary of the abyssal plain at the 2000- 

 fathoms line, we may consider the area between the 2000- 

 and 1500-fathoms lines as an intermediate zone between the 

 abyssal plain and the continental slope. In this zone the 

 "Challenger" made 25 hauls with trawls and dredges, with the 

 result that three times as many fishes per haul, and twice as 

 many invertebrates, were captured as on the abyssal plain. The 

 "Michael Sars " made 3 hauls with the trawl in such depths, 

 which, compared with our results from the abyssal plain, are 

 very interesting, and invite inspection of their details : — 



Station 35. South of the Canaries, 1424 fathoms (2603 metres). Trawl dragged 

 two hours. Result of haul : Many silicious sponges (including 

 Hyalonetfia), hundreds of holothurians, large prawns {Benthesicymus, 

 n.sp.), 18 bottom-fish (9 Macrurids, i Bathysmirus, 2 Halosau- 

 ropsis, 5 Alepocephalus, i Hariotta). 



„ 53. South of the Azores, 1430 to 1570 fathoms (2615 to 2865 metres). 

 Trawl dragged three or four hours. Result of haul : 2 large and 

 many small sponges, 3 mussels, 5 cirripeds {Sca/pellum), 30 large 

 prawns {Aristeopsis), 15 hermit crabs, 5 Pentacheles, i large white 

 decapod {Mutiidopsis, n.sp.), 500 holothurians, 39 bottom-fishes, 

 (17 Macruriis, 5 Halosauropsis, 2 Benthosmirus, 2 Bathysaurus, 

 2 Bathypterois, 6 Alepocephalus, 5 Synaphobranchus). 



„ 88. North of the Azores, 1700 fathoms (3120 metres). Result of haul : 

 a great number of holothurians, sea-urchins, starfish, ophiurids, 

 some crustaceans {^Polycheles, Mti?ndopsis, Farapagurus), 2 1 bottom- 

 fishes (17 Macrurus, i Bathysaurus^ 3 Histiobranchus\ 



These hauls plainly show that the appliances of the " Michael 

 Sars" were excellently suited for the capture of bottom organisms, 

 fish as well as invertebrates. Indeed in one single haul (Station 

 53) we caught nearly as many individual bottom-fishes as the 

 " Challenger " captured in its twenty-five hauls in depths between 

 1 500 and 2000 fathoms. I think we are justified in concluding 

 that the vast difference between our captures on the abyssal plain 

 and these three hauls in 2600 to 3200 metres represents an 

 actual difference in the abundance of animal life in the two 

 regions. The fauna of the abyssal plain must be very poor 

 compared with the more abundant life met with, at all events 

 in the Atlantic, in depths of about 3000 metres and less, where 

 the fauna is infinitely richer in number of species as well as in 

 number of individuals. Perhaps the most striking contrast is 



