ON COLLECTING SHELLS. 



141 



fisheries are so rudely made as to injure tlie more delicate 

 marine animals, and suffer all the minute thin2:s to escape. It 

 is therefore necessary to haye instruments specially adapted for 

 the naturalist's work. 



Fig. 33. Plan of the Framework of a Dredge, reduced to f. 



Fig. 33 is a plan, and Fig. 34 a side- 

 view, of a small dredge, belonging to Mr. 

 J. S. Bowerbank, and suited for such 

 work as a private collector might do on 

 the English coast. It is made of wrought 

 iron, with movable joints, so as to fold 

 up and carry in the hand. The bag attached 

 to the dredge is formed of two pieces of 

 raw hide (A, h), connected at the ends 

 and bottom by net [n) made of cod-line, 

 to allow the water to escape; and is 

 fastened to the frame with copper wire, 

 through the eyelet-holes. The towing- 

 rope is attached to the rings (r, r), and 

 when thrown overboard it scrapes with 

 one or other of the cutting edges (e, e). 

 The opening is made narrow, to prevent 

 the admission of large and heavy stones. 



Dredging should not be attempted in a 

 rowing -hoot, unless near the shore, in 

 smooth water, and with a depth not ex- 

 ceeding 5 or 10 fathoms. It may be 

 managed in a light boat by two persons ; 

 one rowing, the other holding the rope of 

 the dredge which is passed overboard near 

 the stern. 



The whelk and oyster-dredgers employ 

 a decked sailing-vessel, and work several 

 dredges simultaneously, each requiring a person to manage it. 



Fig. 34. 



