[27] INSTRUCTIONS FOR COLLECTING MOLLUSKS DALL. 



rectangle. The lower and upper edges in front are liamiuered so as to 

 flare a little, like the edge of a chisel, [a, a, Fig. 2) thus plowing up the 

 Ibottom over which the dredge is pulled. The edges of the short verti- 

 cal sides are left without this bevel. In each side are two holes, ( h, h , Fig. 

 3) in which are inserted the Y-shaped ends of the arm (Fig. 5) of each 

 side, made of a slender (about three-eighths of an inch) iron rod. The 

 anterior part of each arm ends in a ring formed by turning the end of 

 the rod round. Parallel with and near to the back edges of the frame 

 is punched a row of holes, as many as may be convenient. By means 



oh 



o^ 



/a^ h 



Tigs. 1 and 3. — Dredge frame. 



of rivets through these holes a thin strip of galvanized iron is attached, 

 extending, on the outside, entirely around the back edge of the rectangle. 

 The hinder edge of the galvanized iron extends about an inch behind the 

 hinder edge of the frame. This is perforated with a row of small holes 

 about an inch apart, extending entirely around the edge. To these holes 

 a net (fZ, Fig. 2) and two flaps of stout canvas {c^ (?, Fig. 2) are laced with 

 copper or galvanized iron wire. The object of the strip of galvanized 

 iron is to hold the net away from the iron frame, which always rusts. 

 This rust would very soon destroy the net, but if the latter is separated 

 from the iron by the galvanized strip which does not rust, a single net 

 may sometimes be used for a whole season, without need of repair. The 



Fig. 2. — Dredge frame Tritli net and canvas. 



edge of the net to be laced on is placed inside of the galvanized iron. The 

 front edges of the two strips of canvas are placed outside. These stri^DS 

 of canvas should be a little wider and about a foot longer than the net 

 when it is wet and stretched. The lacing is done by sharpening the ends 

 of a piece of copper wire or well galvanized wire, making holes in the can- 

 vas with an awl and passing the wire in and out as if sewing, so that 

 the edges of the canvas, of the net, and the thin strip of galvanized iron 

 are closely and carefully fastened together. The object of the strips of 

 canvas is to receive the friction of the bottom, thereby preventing undue 

 wear upon the net. As in sinking the dredge they are very apt to curl 



