ON COLLECTING SHELLS. 2*71 



animals, seldom obtained at other periods except by the dredge. 

 Mau}^ bivalves bur}" in sand and mud at extreme low-water, and 

 may be obtained alive by digging with a spade or fork ; others 

 may be found boring in piles and rocks, and require the hammer 

 and chisel for their extraction. Bivalves may be boiled, and 

 their soft parts removed when the shells gape. Care should be 

 taken not to injure the ligament, or hinge, especially in the genera 

 (like the Anatinidre) provided with an ossicle. 



Mr. Joshua Alder remarks that " in collecting among rocks 

 the principfil 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 it for some time 

 in a basin of sea-water, when the little mollusks will generally 

 creep out. If the shells onl}' are wanted, the surer and more 

 read}- way is to plunge the weed into fi-esh-water, when the 

 animals immediately fall to the bottom." Sea-fishes and fowl 

 purchased for the table should be cai'efully examined when opened 

 for cleaning ; shells are frequently obtained in this way : — which 

 has furnished conchologists with many fine specimens. 



The floating mollusca of the open sea, especiall}' in tropical 

 latitudes, are comparatively little known. Good drawings, and 

 descriptions made from the life, are most valuable. " Of the 

 animal of the Spirula, entire specimens are still greatly wanted. 

 If captured alive its movements should be watched in 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 move- 

 ments, and when at rest. The chambered shell should be opened 

 under water, to ascertain if it 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 more precision 

 and facility from its larger size." — (Owen.) 



The towing-net used by Mr. McGillivray " consisted of a bag 

 of bunting (used for flags) 2 feet deep, the mouth of which was 

 sewn round a wooden hoop 14 inches in diameter; three pieces 

 of cord, li foot long, were secured to the hoop at equal intervals 

 and had their ends tied together. When 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 

 the line required was regulated by the speed of the vessel at the 

 time, and the amount of strain caused bj''the partially submerged 

 net." — Voy. Rattlesnake, 



A trawl-net for use on sea-bottoms is thus constructed : ,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 in length, and about 8 inches square 

 The niet is about 30 yards in depth, and has a couple of pockets 



