58 



Insects. 



Cycloj)sina Rivillii, Baird. Body of animal nearly cylindrical, 

 slightly sinuated on each side, about the middle of first articulation. 

 Tail short. Antennae very long, nearly double the length of the body, 

 numerously articulated, and covered with long setae. The last arti- 

 culation of tail is bifurcated, each division giving out four rather long 

 filaments, which are strongly and beautifully plumose or feathered ; 

 these plumose filaments could be distinctly seen by the naked eye, and 

 form a very marked character of the species. 



a. Cyclopsina Slabberi. b. Cyclopsina Rivillii. The lines show the respective sizes. 



Inhabits the North Atlantic Ocean. "May 22, 1832, in lat. 10° 53' 

 N. long. 20" 30' W., the water appearing luminous during the night, I 

 drew up a bucket-full to be examined in the morning." " Found se- 

 veral animalcules in the water drawn up last night, one of which is 

 the species described above." — Private Journal. 



M. Godeheu de Riville, in a paper on the luminousness of the sea 

 published in the Mem. Savans Etrang. vol. iii., describes an insect 

 which he caught in the sea off Ceylon, and found to be luminous in 

 the water, which very closely resembles this species, (vide p. 275, t. 10, 

 fig. 5). He gives it two eyes, and the whole figure is exaggerated, but 

 the plumose tail is given with very considerable accuracy, and I have 

 little doubt it is the same species as the one here described. He calls 

 it, fi-om the extreme beauty of the tail, the " Paon de Mer." M. de 

 Riville (after whom I have named the species), says " the plume with 

 which the tail is ornamented deserves particular attention. The ex- 

 tremity of the body is terminated by a fork, each branch of which 

 has a projection, to which are attached four true plumes of a rose co- 



