readily pass into its mouth and accumulate in the pouch at its end. After
drifting with the tide for six or seven hours the trawl is hauled up, the
marketable fish are picked out, the others thrown away, and the trawl
sent overboard for another operation.

More than a thousand sail of well-found trawlers are constantly engaged
in sweeping the seas around our coast in this way, and it is to them that
we owe a very large proportion of our supply of fish. The difficulty of
trawling, like that of dredging, rapidly increases with the depth at
which the operation is performed; and, until the other day, it is
probable that trawling at so great a depth as 100 fathoms was something
unheard of. But the first news from the _Challenger_ opens up new
possibilities for the trawl.

Dr. Wyville Thomson writes ("Nature," March 20, 1873):--

"For the first two or three hauls in very deep water off the coast of
Portugal, the dredge came up filled with the usual 'Atlantic ooze,'
tenacious and uniform throughout, and the work of hours, in sifting, gave
the very smallest possible result. We were extremely anxious to get some
idea of the general character of the Fauna, and particularly of the
distribution of the higher groups; and after various suggestions for
modification of the dredge, it was proposed to try the ordinary trawl. We
had a compact trawl, with a 15-feet beam, on board, and we sent it down
off Cape St. Vincent at a depth of 600 fathoms. The experiment looked
hazardous, but, to our great satisfaction, the trawl came up all right
and contained, with many of the larger invertebrate, several fishes....
After the first attempt we tried the trawl several times at depths of
1090, 1525, and, finally, 2125 fathoms, and always with success."