298 ZOOLOGY. 



we have detected the species in the Pacific, are 30 

 N. and 32 S. Between the Equator and the parallels 

 of 5 N. and S. lat. they were particularly abundant. 

 They obtain in the Mediterranean ; and are occasionally 

 driven, by heavy gales, across the warmer seas, even to 

 the western shores of Great Britain. I have on nu- 

 merous occasions captured this shell-fish at night, and 

 am satisfied that they are not phosphoric ; although the 

 Rev.Wm.Kirby, in his " Seventh Bridgewater Treatise," 

 asserts that they possess this quality in a very high 

 degree. Neither have they the power of collapsing their 

 float and sinking at will, as is stated by the same author. 

 When the mollusc is captured, and confined in a pan of 

 sea water, the float undergoes no change ; and the shell, 

 consequently, is maintained buoyantly on the surface ; 

 the animal frequently protrudes its head from the shell, 

 in an inquiring manner, and, when handled, retires, like 

 a snail, within the deeper recesses of its dwelling, re- 

 tracting at the same time its aeriferous float, which fills 

 the aperture of the shell. When the entire mollusc is 

 immersed in spirit or dried in the sun, the float remains 

 inflated, and attached to the body for several weeks ; 

 although it ultimately becomes detached, collapses, and 

 can be but seldom exhibited in a preparation. 



Janthina Globosa occurred to us very rarely, and is, 

 perhaps, never found assembled in such large quantities 

 as the species fragilis. It differs from the latter, not 

 only in the shape and more delicate pink hue of its 

 shell, but also in the markings of its float. 



In the course of the Narrative I have had occasion to 

 mention a yellow and very rare species of this genus ; 

 and for which I should propose the name Janthina 

 lutea. 



