40 



be propelled by sails if sufficient care be taken to graduate the 

 amount of canvas to the strength of the wind, in order that the 

 dredge may move slowly over the bottom. Oars are safer, if the 

 force is at command ; and in a tide-way, the tide alone may move 

 the boat with sufficient power, the rope being made fast amidships, 

 or towards the bows, according to the strength of the current. 

 Dredging may be carried on at all depths inside of 200 fathoms. 



Instruments for Collecting. — For shore collecting, a broad 

 flat basket, with jars or tin-cans, of various sizes, for the smaller 

 and more delicate animals, which should be brought home in sea- 

 water. A spade, trowel, and a strong knife for detaching limpets 

 and tunicates from the rocks. A small dip-net is quite indispensa- 

 ble. In dredging, besides the baskets and bottles, one or more 

 buckets are necessary, as many of the larger animals, such as star- 

 fishes, are fragile, and can only be brought safely home in sea-water. 

 And, above all, there should be wire-sieves for washing out the 

 sand or mud brought up from soft bottoms. 



Preservation of Specimens. — Alcoholic fluid is the only me- 

 dium in which marine invertebrates can be properly preserved, shells 

 and corals alone being excepted. Dried specimens are always io 

 danger from dampness and breakage, and when sent to the Museum, 

 seldom reach their destination uninjured. In placing the specimens 

 in kegs, cans, jars, or bottles, a few rules should be carefully ob- 

 served : 1st. Never crowd tkem too much ; a bottle should be not 

 more than half filled with specimens, but must be always entirely 

 filled with alcohol. 2d. Adapt the bottles to the size of the 

 specimens, placing small ones in small bottles, or, if very minute, 

 in homoeopathic vials. 3d. Never put soft and delicate forms with 

 hard or spinous ^ones, which would injure them in any agitation. 

 Each jar or bottle should contain specimens from one locality and 

 station, which should be indicated in full on the label — the nature 

 of the ground, distance from low water mark, and, if dredged, the 

 depth of water being noted. In the larger kegs or cans, if speci- 

 mens from more than one locality are included, each should have 

 a parchment label attached, with the notes written in ink. 



