MARINE BIOLOGICAL STATION AT PORT ERIN. 



75 



In order to collect animals which are not found 

 between tide-marks, the naturalist has to scrape the 

 bottom of the sea with a dredge or trawl, or skim the 

 surface for minute swimming and floating organisms by 

 means of the tow-net. A figure of the naturalist's dredge 



Fig. E. — Simple Tow-net, 

 with Electric Lamp. 



Fig. F. — Hensen's Vertical 

 Plankton Net. 



lying on the sea-bottom is seen at the end of the Preface, 

 and fig. D shows the same collecting instrument when it 

 has been hauled up full and is being emptied out on the 

 deck of the steamer, 



