ON COLLECTING SHELLS. 139 
captured alive, its movements should be watched 1n 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 sheil 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 obseryations, 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 decp, the mouth of which was 
sewn round a wooden hoop 14 inches in diameter; three pieces 
of cord, 13 foot long, were secured to the hoop at equal inter- 
vals 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 by the partially 
submerged-net.” + 
Trawling.—Mr. John W. Woodall,of Searbro’, has kindly fur- 
Z f, 
ba PS. 
_A wea 
aul cl 
“SS i 
Ft hh SS 
‘ ScReSe SSS 
yd WRK SSO, 
ENS Ae x 
Fig. 32. A Trawl-net. A. Side view; B. Net in op ration; ©. Plan. 
nished the following sketches and particulars :—‘ B, Fig. 32, is 
intended to represent a trawl-net at work on the bottom of the sca. 
4 Admiralty Manual of Scientific Inquiry. 8vo. Lond. 1849. 
{+ Voyage of H.M.S. Rattlesnake, vol i. p. 27. 
