to the Antarctic Regions. 39 



Drawings of these changes are very desirable, and when practicable 

 the eggs and young ones in different stages should be preserved in 

 spirit in short glass tubes. The smaller oceanic Crustacea offer a 

 prolific and hitherto unexplored field of investigation. 



Among the floating Mollusca likely to be met with in the tropical 

 latitudes is the Spirula, a small Cephalopod with a chambered shell. 

 An entire specimen of this rare Mollusk is a great desideratum ; and 

 if it should be captured alive, its movements should be watched in a 

 vessel of sea water, with reference more especially to the power of 

 rising and sinking at will, and the position of the shell during those 

 actions. 



The chambered part of the shell should be opened under water, 

 in order to determine if it contain a gas ; the nature of this gas 

 should likewise, if possible, be ascertained. As a part of the shell 

 of the Spirula projects externally at the posterior part of the animal, 

 this part should be laid open in the living Spirula, in order to ascer- 

 tain how far such mutilation would affect its power of rising or 

 sinking in the water. In the event of a living Pearly Nautilus (Nau- 

 tilus Pompilius) being captured, the same observations and experi- 

 ments should be made on that species, in which they would be at- 

 tended with more precision and facility, as the species is much larger 

 than the Spirula, and its shell external. The towing-net should be 

 kept overboard at all practicable periods, and drawn up and examined 

 at stated intervals, as some of the rarest marine animals have been 

 taken by thus sweeping the surface of the sea. 



A sketch or drawing of Molluscous and Radiate animals, of which 

 the form and colour are liable to be materially altered by death, or 

 when put in spirit, will aid materially in rendering the description 

 of the species useful and intelligible. The Echinodermata and As- 

 terias echinus, and similar forms, should be soaked in fresh water 

 previously to their being put into spirit. 



Care must be taken not to crowd too many soft-bodied Inverte- 

 brata in the same bottle, and to change the spirit or preserving liquor 

 at least once, if not oftener. 



2. Fishes. 



The mode and speed of swimming, living colour, temperature, 

 and any other peculiarity, should be noticed before placing the spe- 

 cimen in spirit. 



In very large specimens of the Shark or Ray kind, a section of the 

 jaws, with a part of the vertebral column, should always be pre- 

 served as wet preparations, and the remainder of the jaws and ver- 



