6 Marine Invertebrates 



fixed to a wooden handle. The bag usually measures about i foot in 

 diameter at the opening and 18 inches in depth. The netting may vary 

 from i inch mesh at the top with % inch at the bottom for larger speci- 

 mens, to % of an inch at the top with % inch mesh at the bottom for 

 smaller forms. For collecting minute organisms a bag made of bolting 

 silk Nos. 12, 16, or 20 may be substituted. The handle is usually from 

 6 to 7 feet long, but of course may be increased to any desired length. 



Fig. 2. — The pile scrape net. 



For picking up small specimens floating on the water a small dip net 

 about 6 inches in diameter is sometimes preferable. 



The pile scrape net. This modification of the dip net is used for col- 

 lecting organisms growing on piling and other underwater structures. 

 The metal ring of the net is bent in such a way as to make it fit the curva- 

 ture of the piling (Fig. 2) ; it is about % 6 °f an mcn m thickness and 12 



K-,— Ut -- It^t 



Fig. 3. — The square scrape net. 



inches in diameter with the curved scraper 1 inch in width. Attached 

 to this frame is a net 18 inches in depth with the mesh % of an inch at 

 the top and % of an inch or less at the bottom. The metal blade which 

 is welded to the lower part of the iron frame works as a cutting knife 

 when the net is pressed against the piling and is pulled up. The length 

 of the handle varies according to local conditions from 6 to 20 feet. 



The square scrape net. This type is a modification of the pile scrape 

 net from which it differs only in the shape of the frame, which is not bent 

 (Fig. 3) as it is in the former type, and is provided with a straight 

 cutting blade attached to the base. This net is very useful in collecting 

 organisms growing on walls of various underwater structures such as 



