306 ZOOLOGY. 



a-half to two inches in circumference. The body is 

 cylindrical, and rounded and impervious at one extre- 

 mity, while the opposite is flat, and perforated in its 

 centre by a circular orifice, conducting to a capacious 

 straight tube that occupies the interior of the body. It 

 is colourless, and its surface is studded with pearly 

 tubercles, perforated at their apices, and spread with 

 many papillous appendages. The structure of the body 

 is gelatinous, and contains myriads of small brown 

 specks, in which the phosphorescent power, for which 

 this mollusc is so remarkable, would appear to reside. 



When assembled in the sea, and, as is usually the 

 case, near the surface, these creatures present a gor- 

 geous spectacle; their vivid phosphoric light being 

 sufficient to illuminate, not only the extent of ocean they 

 occupy, but also the air above, rendering all surround- 

 ing objects visible during the darkest night, and per- 

 mitting a book to be read on the deck, or near the stern- 

 cabin windows of a ship. They are occasionally col- 

 lected together in incredible numbers : on two occa- 

 sions, at midnight, in lats. 2o and 4 N., Atlantic 

 Ocean, (when I had the good fortune to see these 

 molluscs in their zenith of splendour,) the ship sailed 

 over many miles of water which they had illuminated, 

 and in which they were so densely crowded* as to be 

 taken to any amount by buckets or nets. When cap- 

 tured they exhibited no signs of animation, and emitted 

 a peculiar half-fishy odour. When kept in a vessel of 

 sea-water, and allowed to be tranquil, their light was 

 withheld, or only sparingly displayed ; but when they 

 were handled, or the water in which they were con- 



* We have also seen examples of Pyrosoma, though less numerous, in 

 the Pacific Ocean, on the Equator, and in 3" S. A solitary specimen 

 was captured in so high a latitude as 28 N. 



