436 MANUAL OF THE MOLLUSCA. 



Mr. Joshua Alder roinaiks that, " in collecting among rocks the principal ^ 

 thing is to look close, particularly in crevices and under stones. Minute species « 

 inhabiting sea-weed are best obtained by gathering the weed and immersing j 

 it for some time in a basin of sea-water, when the little moUusks will generally * 

 creep out. If the shells only ai'c wanted, the surer and more ready way is i 

 to plunge the weed into fresh-water, when the animals immediately fall to the !! 

 bottom." 



The float'mff mollusca of the open sea, especially in tropical latitudes, J 

 are comparatively little known. Good drawings, and descriptions made from J 

 the life, are most valuable. " Of the animal of the Spinel a, entire specimens .^ 

 are greatly wanted. If captured alive, its movements should be \vatched in j 

 a vessel of sea-water, to see whether it has the power of rising and sinking at.^ 

 will ; its mode of swimming, and position during these movements, and when.j 

 at rest. The chambered shell should be opened under water, to ascertain if it J 

 contain a gas, the nature of which should if, possible, be made out. The pearly'' 

 nautilus requires the same observations, which would be attended with moren 

 precision and facility from its larger size." {Owen)* 



The tov)'ing-net used by Mr. Mc Gillivray "consisted of a bag of hunting" 

 (used for flags) two feet deep, the mouth of which was sewn round a woodea < 

 hoop li inches in diameter ; three pieces of cord, a foot and a half long, were \ 

 secured to the hoop at equal intervals and had their ends tied together. ' 

 Wlien in use the net was towed astern, clear of the ship's wake, by a stout ■ 

 cord secured to one of the quarter boats, or held in the hand. The scope of 1 

 the line required was regulated by the speed of the vessel at the time, and the i 

 amount of strain caused by the partially submerged i.et.'"t 



Trawling. — Mr. John W. Woodall, of Scarbro', has kindly furnished the ( 

 following sketches and particulars; — "Fig. 227, is intended to represent a^ 

 trawl-vet, at work on the bottom of the sea. The side frames are of iron, | 

 the upper beam of wood, and the lower edge of the net is kept down to the \ 

 ground by means of a chain, which is wolded or wrapped round with old rope. | 

 The beam is generally from 40 to 50 feet iu lengtli, and about 8 inches \ 

 square. The net is about 30 yards in depth, and has a couple of pockets \ 

 inside. The end is untied when the net is hauled on board for the purpose 

 of taking the tish out. These nets can only be worked where the bottom of ' 

 the sea is free from rocks. They are used by boats of 35 to 60 tons, manned 

 by crews of from 4 to 6 men, and 2 to 3 or four boys. In the vicinity of \ 

 Scflrbro' they fish between the shore-reefs and the off rock which is 4 — 10 ' 

 miles from land; the bottom is sand or clay, with 4—15 fathom water on i 

 the land-si<le, and 17 — 25 fathoms on the off side." Immense quantities of ' 

 Crustacea and shell- fish are taken witli the trawl, as well as ground-fish. 



* Admiralty, Manual of Scientific Inquiry. 8vo. Lond. 1S49. 

 •f Voyage of H. M. S. Rattlesnake, vol. I. p. 27. 



