APPARATUS USED WITH PLANKTON NETS 



193 



with certainty under all conditions. This type is illustrated about half size in Fig. 17 

 and does not call for detailed description. 



Fig. 18. Closing meqjianism for small horizontal nets: for explanation see text. 

 Two kinds of messenger are ordinarily used with these mechanisms, both of the torpedo 

 pattern described by Knudsen;^ they weighed 405 and 615 grm. respectively. 

 1 Knudsen, Pub. Circ, Cons. Explor. Mer, 77, p. 15, fig. 5, 1920. 



