ON COLLECTING SHELLS. 141 
fisheries are so rudely made as to injure the more delicate 
marine animals, and suffer all the minute things to escape. It 
is therefore necessary to haye instruments specially adapted for 
the naturalist’s work. 
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 moyable joints, so as to fold 
up and carryin the hand. The bag attached 
to the dredge is formed of two pieces of 
raw hide (h, h), connected at the ends 
and bottom by net (m) 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 (7, 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-boat, unless near the shore, in 
smooth water, and with a depth not ex- 
ceeding 5 or 10 fathoms. It may bey 
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. 
