

100 
On a DEEP SEA TOW-NET for OPENING and 
SHUTTING UNDER WATER. 
By Wiuuiam E. Hoyts, M.A. (Oxon.), F.R.S.E. 
(Communicated by Professor Herdman.) 
With Plate III. 
[Read 9th November, 1888. } 
INTRODUCTION. 
A conicau net of muslin or other fine-meshed material has 
long been a favourite instrument for collecting the smaller 
denizens of the surface and sub-surface water, but, so far 
as I am aware, this apparatus was first used systematically 
at any considerable depth by the naturalists of the 
‘“‘Challenger’’ Expedition. The more extensive the obser- 
vations made with it, the greater became the desire to 
know with certainty at what depth the animals captured 
in it had been obtained. 
As the investigation of the deep sea became more 
frequent, attempts were from time to time made to con- 
struct an apparatus which could be lowered shut to a 
given stratum of water, then opened and towed for a time 
in that condition and finally closed before being again 
brought up. ‘The earliest of these is, I believe, the 
‘“‘oravitating trap” of Captain Sigsbee.* It consists of 
a cylinder which slides down a rope, and is constructed to 
descend open through a stratum of water of any desired 
thickness, and then to close before being hauled up. Its 
* Sigsbee, Bull. Mus. Comp. Zool., vol. vi., pp. 155—158, pl., 1880; see 
also Agassiz, Cruises of the ‘‘ Blake,” Bull. Mus. Comp. Zool., vol. xiv., p. 36, 
1888. 



