[33] INSTRUCTIONS FOE COLLECTING MOLLUSKS DALL. 



very well. When the dredge is emptied, the net should be turned 

 inside out before it is returned to the bottom, and thoroughly washed, 

 so that animals obtained at one haul shall not accidentally become 

 mixed with those of the next. 



THE USE OF THE DREDGE WITH A SAILBOAT. 



In dredging from a sailboat deeper water can be reached than is 

 convenient with a row boat. A person unaccustomed to the use of a 

 sailboat will find it necessary to obtain the services of some one who 

 is, since the management of a boat of this kind hampered by the weight 

 of a dredge and line is no easy matter. If supplied with a comj)etent 

 sailing-master the method of work will differ little from that used in a 

 row boat, except that the direction in which dredging can be done will 

 be limited by the direction of the wind, and, by way of comj)ensation, 

 a much larger space of bottom can be dredged over in the same time. 



Use of tJie trmvl net. — In collecting with a sailboat it will often be 

 found advantageous to make use of a trawl. The ordinary trawl con- 

 sists of an iron frame somewhat like the two runners of a sled, fastened 

 to each other by a heavy bar of iron, to which a large net is attached. 

 The lower edge of the net in front is weighted with oblong leaden 

 sinkers, so as to drag upon the bottom. A trawl of this kind is much 

 used by fishermen, and sometimes in obtaining oysters. Such a trawl, 

 though the coarseness of the meshes renders it unfit to collect minute 

 material, will nevertheless frequently bring up dead shells, .stones, and 

 other objects of larger size covered with sessile animal life, together 

 with large-sized mollusks, and in this way specimens may be obtained 

 which it would be difficult to obtain by means of a small dredge. The 

 improved trawl used in deep-sea dredging will be found described in 

 works on deep-sea dredging, to which reference lias already been made. 

 In case the collector has an opportunity to accompany a fishing vessel 

 on a trawling expedition he may obtain interesting forms which are 

 brought up with the fish and other commercial products of the sea. 



The trawl line. — Line fishermen use the word trawl in another sense, 

 applying it to a line buoyed at each end, to which baited hooks are 

 attached at short intervals, and which is set for fish. On this sort of a 

 trawl, or, more properly, trawl line, large carnivorous mollusks frequently 

 attack the bait, and when the fisherman examines his line, are often 

 found sticking to it. A species which can not be dredged, owing to the 

 irregular and rocky character of the bottom, may sometimes be obtained 

 by making arrangements with fishermen to save the shellfish which 

 they find attached to their trawls. 



The baited net. — Another mode of collecting, which is available for 

 persons having the use of a boat, over bottom which does not admit 

 the use of the dredge or trawl net on account of its irregularity, is by 

 means of a net such as is ordinarily termed a crab net by fishermen. 

 Such a net is circular and attached to a large wooden hoop from 6 to 

 21387— ]S:o. 39 3 



