24 BULLETIN OF THE 
tion,? Chun was provided, as he says, with a line for pelagic fishing of a 
length of 1,600 meters. 
During the journey Chun made seven casts, at depths varying from 
500 to 1,600 meters. ‘The casts are certainly not numerous enough to 
furnish a basis for a general theory. Two of the casts were at depths of 
500 and 1,000 meters, not very distant from Cape Finistére, while an- 
other cast of 500 meters was made off Funchal, and the cast of 1,600 
meters was made between Teneriffe and Gran Canaria, where he speaks 
of making a pelagic haul at a depth of 1,600 meters with a line only 
1,600 meters long. He must, of course, have lowered his net vertically, 
and Chun can hardly expect any one practised in dredging or towing to 
accept the depth he gives as the correct bathymetrical limit at which 
the two specimens he brought up were collected. Furthermore, all 
of these casts except one, perhaps, are open to the objection of having 
been made at comparatively small distances from land ; and, taking 
Chun’s own account, the casts of 500 meters, say 250 fathoms, contain, 
judging from his list, about the same amount (somewhat less) of pelagic 
material as was found in our “ Albatross” hauls with the tow-nets at 
depths of about 200 fathoms. 
Furthermore, he says: “kam es bei den friiherhin im Mittelmeer an- 
gestellten Versuchen gelegentlich vor dass durch den starken seitlichen 
Druck, welche die sich auslésenden Drahte auf den mit einem Schrau- 
bengewinde versehenen Messingstab ausiibten, ein Offnen und Schliessen 
des Netzes nicht erfolgte, anderseits blieb nach dem Schluss des Netzes 
gelegentlich ein schmaler, etwa fingerbreiter Spalt zwischen den bewe- 
glichen Hilften des Rahmens frei.” 
I need not say that an opening of half an inch wide and nearly two feet 
long at the mouth of the net will, in its ascent through a distance of 
200 fathoms of the upper belt of the pelagic fauna, suffice to sift into 
the bag enough material to vitiate all accurate conception of what lives 
below that belt. In his expedition to the Canary Islands, these defects 
were said to be remedied by Chun, and the modified net was used by 
him during his voyage at depths of 500, 1,000, and 1,600 meters. But 
Hensen is of the opinion that the modified net is still defective, and that 
its results cannot be relied on. There seems to be no reason why these 
self-closing nets should not be placed serially on a line, as are ther- 
mometers, and then we may expect to get accurate results. If this be 
impracticable, we can, at any rate, use the nets at the same locality at 
1 Untersuchungen iiber die pelagische Fauna der Canarischen Inseln, von Carl 
Chun, Sitzungsb. d. Konig. Preuss. Akad. d. Wiss. zu Berlin, XXX., 1889, p. 519. 
