172 THE PYROSOMA. 



tumultuous ; the bright waves heave up, roll, and 

 break in shining foam. At other times, large 

 sparkling bodies, resembling the forms of fishes, 

 pursue each other, disappearing and bursting forth 

 anew. 



In some cases, thej luminosity of the ocean is 

 owing to the sea-nettles, which are scarcely per- 

 ceptible without the assistance of a microscope. 

 All, however, are not equally minute ; the cydip- 

 pes, in which the cilia would seem to be most 

 vividly phosphorescent, are of considerable size ; 

 the girdle of Venus, as it glides rapidly along, has 

 the appearance of an undulating riband of flame, 

 several feet in length ; and many larger crea- 

 tures shine with such dazzling brightness, that they 

 have been described by navigators as resembling 

 " white hot shot, visible at some depth beneath the 

 surface." 



Among luminous beings the Pyrosoma holds a 

 prominent place. Mr. Bennett, in one of his voyages, 

 observed the sea presenting one mass of phosphoric 

 light, extending to a considerable distance around 

 the vessel. So powerful was it as to illuminate the 

 sails, and to permit a book of small print to be read 

 with facility near the windows of the stern cabins. 

 Above this bright field, numerous sea-fowl were 

 hovering in search of their prey. The light ap- 

 peared to be entirely owing to the Pyrosomata. 

 Specimens taken from the sea and placed in a vessel 

 containing sea-water, ceased altogether to emit light, 



