CHAP. III. ] TENERIFFE TO SOMBRERO. 223 
the bottom, species occur which have been detected neither on 
the surface nor at 1000 fathoms, the greatest depth at which 
the tow-net has yet been systematically used ; and specimens 
taken near the bottom of species which occur on or near the 
surface give us the impression of being generally larger and 
better developed. The results from the tow-net are not so 
Fia. 54.—Haliomma (sp.n.). From the surface. Two hundred times the natural size. 
directly satisfactory as those from the trawl or dredge, which 
usually brings up animals which we know, from their nature, 
must have lived on the bottom, and it requires a little consid- 
eration to arrive at their precise value. We have not yet con- 
trived a tow-net which can be sent down closed, which will 
open its mouth when it reaches a certain depth, and close it 
again after a certain lapse of time; although there is little 
doubt that such a net might be made easily enough. At pres- 
