10 ANIMAL PARASITES AND MESSMATES. 



together an association which probably redounds to the * 

 advantage of both. 



Without quitting our own sea-coast, we find an asso- 

 ciation of the same kind between young fishes (Caranx 

 trachurus) and a beautiful medusa {Chrysaora isocela). 

 This sea nettle often encloses several young specimens 

 of Caranx, which we are surprised to see issuing full of 

 life from the transj)arent bodies of these polyps. Indeed, 

 it is not rare to find other fishes in the medusae. Dr. 

 Gunther, who has arranged with so much care the rich 

 collection of fishes in the British Museum, has shown us 

 some specimens of the Lahrax lupus, and of the Gaster- 

 osteus, which had been obtained from the interior of 

 different medusae ; and these associations have been also 

 remarked by various distinguished observers, among 

 whom we may mention Messrs. Sars, Eud. Leuckart, and 

 Peach. The captain of the frigate Jouan, when in the 

 Indian Sea, on October 26th, 1871, in 18° 20' N. lat., 

 and 60° 30' E. long., that is to say, about 200 leagues 

 to the west of the Laccadive Islands, saw, in very fine 

 weather, the sea, which was at that time very calm, covered 

 with medusae, and the greater part of these were escorted 

 by many little fishes of the genus Ostracion, the species of 

 which he was unable to ascertain. It is probable that 

 the school of medusae set in motion certain animals which 

 are eagerly sought after by the Ostracions. 



The Pilot is a fish of which much has been recorded ; 

 fishing for it is one of the principal recreations of sailors 

 during their long voyages. Some assure us that it 

 snaps off the bait, without touching the murderous hook 

 which threatens the shark; and as it never quits its 

 companion, others have supposed that it lives on the 



