Mil/iocL^ ill riaiiktoji Jiircstigatioi/s. 2") 



Fi<;. 9. — Kim of cover of net. sliowing clamp for holding cover in 

 place. X 1. 



c. Clamp, in position. /. w. Inner wall of trough. 



'•'. Clamp, released. o. xo Outer wall of trough. 



coo. Cover. xtr. Strap of clamp. 



/. Foot of cover. lo. Wing of cover. 



Fi<;. 10. — Same, showing method of fastening outer silk net; cover 

 partially removed. X 1. 



/'. I. Butchers' linen. o. ?;. Outer net. 



cd. Cord. 

 Other lettering as in Figure 9. 



Plate V. 

 The plankton pump. X ixt- 



Plate VI. 

 The plankton pump in operation. 



Plate VII. 

 The centrifugal machine. X %. 



