154 ON THE MEDUSAE. 



principal claims which they have always had to the interest 

 of observers, and to have laid before the reader all the import- 

 ance of the researches towards which I am going to call his 

 attention. 



" In the midst of the vast seas which our vessels have tra- 

 versed, we, M. Lesueur and myself, have discovered more new 

 species of animals of this kind, than the naturalists of any 

 age or country had made known before us. These numerous 

 species have been described and painted from living indi- 

 viduals ; they have afforded us grounds for a multitude of re- 

 searches and important discoveries. On the other hand, all 

 the authors who have written on Medusae have been laid un- 

 der contribution: I have myself undertaken the task of ex- 

 tracting from many hundred volumes in different languages, 

 all that could have any relation to these animals, and M. Le- 

 sueur himself has copied the designs and paintings scattered 

 through the numerous volumes with which he has been en- 

 gaged; and lastly, our recent excursions on the coast of La 

 Mancha, and the shores of the Mediterranean, have placed at 

 our disposal the greater part of the European species which 

 have been described before us. 



u Having so large a fund of materials, we propose to our- 

 selves in this work, to give successively the history of all the 

 species and of all the genera which ought naturally to com- 

 pose this great family of the animal kingdom : we shall treat 

 in detail of the organization and the habits of these singu- 

 lar beings; we shall set forth all that we have been able to 

 discover about their various systems of locomotion, of diges- 

 tion, of generation, &c; we shall relate the series of experi- 

 ments by which we have been led to discover in the Medusae 

 a mode of respiration analogous to that of the more perfect 

 animals, and which, however, has hitherto escaped the re- 

 searches of the most skilful observers; we shall mention the 

 different phaenomena of the phosphorescent property, and we 

 shall dwell with so much the more interest on this subject, 

 since it connects itself more immediately with the great pro- 

 blem of the phosphorescence of the sea. 



" However simple may be the organization of the Medusae, 

 still they are not scattered indiscriminately over the surface 

 of the ocean ; each species has its proper sphere of existence, 

 beyond the limits of which it does not seem to extend. It 

 may be that the temperature of the waves, the nature or the 

 abundance of its food retains it there, or that the limited 

 power of locomotion which characterizes these animals, does 

 not permit them to go far from the places where they have 

 been originally established by nature. Whichever of these 



