318 University of California Publications in Zoology. [Vol.8 



Heincke (1894) describes a "Brut-netz" used at the Helgo- 

 land Station for taking fish-eggs and fry. It is anchored in a 

 current to a float, being lowered open, till it floats out at the 

 desired level. "While in operation it is suspended by a line to 

 the crowfoot running to the usual marginal ring. When with- 

 drawn it is hauled in by a second line running to a second, ring 

 about one-third of the length of the net from its mouth. The 

 terminal ring, as it falls, carries the upper part of the bag across 

 the opening of the second ring and thus closes the net during 

 descent, a principle later employed in the Marsh and Nansen 

 closing-nets. 



The Birge (1895) closing-net devised for limnological explor- 

 ation is adapted only for vertical hauling. It is opened and 

 closed by weights released by messenger. The lid is slid off 

 horizontally from the top of the net in opening and returned 

 in closing. As constructed, the net is cumbersome and ill- 

 adapted to work at sea because of the numerous lines and 

 dangling weights. 



Hensen (1895) mentions a photograph of a Norwegian 

 closing-net drawn by three cables and operated by propellers 

 and clockwork, devised for exploration of currents, and evidently 

 for horizontal towing. He unfortunately gives no clue to its 

 origin and I have found no other reference to it in literature. 

 It seems to have joined the procession of failures. Professor 

 Gran writes me that he does not know the history of this net. 



The Townsend (1896) closing-net is adapted to vertical haul- 

 ing or to towing at the end of an oblique cable (intermediate 

 towing). It is lowered open and closed by messenger. Closure 

 is effected by release by messenger of a lever which shifts the 

 weight of the net upon tow lines which close the semicircular 

 jaws. A sliding weight upon the original tow lines tends to 

 hold the jaws closed. The trip requires very careful adjustment 

 of a bent spring to insure control of its operation and is liable 

 to get out of order. Furthermore, the net open in descent is 

 objectionable, and the system of closing is open to the criticism 

 of uncertainty as to its continuity. The net has not been gener- 

 ally adopted for deep-sea work. 



A folding-ring net for opening and closing by messenger 



