196 CLASS III.— ORDER II. 



temperature, they mistook these little animals for the 

 blossoms of marine vegetation. This error continued 

 many years after the discovery of Peyssonnel, a dis- 

 covery which was forgotten till Trembley's observa- 

 tions on the fresh-water polypi brought to the recol- 

 lection of many members of the Academy of Sciences 

 the marine Polypi of Peyssonnel ; and, thanks to the 

 investigations of Bernard de Jusias and of Guettard, 

 the true nature of the Gorgonias, as well as that of 

 other Polypidoms, remained no longer doubtful. 



Since this period Linneus, Ellis, Pallas, Cavolini, 

 Spallanzani, Bosc, and other learned men, have studied 

 the polypi of the Gorgonias, and have given us the 

 result of their observations ; but their discoveries have 

 not yet dispelled our ignorance respecting their manner 

 of existence, or the nature of their internal organi- 

 sation. 



All the species of Gorgonias are attached to rocks 

 and other marine bodies by a more or less extended 

 base, whose surface is usually deprived of the fleshy 

 substance which covers the other parts of the Polypi- 

 dom. From this base arises a stem, which gradually 

 diminishes in thickness up to the smallest branches, 

 the extremities of which are often setaceous. The 

 branches vary much in their form and respective si- 

 tuation ; they are either dispersed or spring regularly 

 from the sides, sometimes they are found growing 

 double, and at others regularly pinnated ; some are 

 flexible, some straight, some curved, some single, and 

 some anastomosed ; in short, some are found slightly 

 compressed, some nearly flat, and some angular or 

 three- sided, but the greater number are cylindrical. 



