THE ANATOMY OF ALOYONIUM DIGITATUM. 347 



which it can raise or sink itself at pleasure in its tube ; all 

 these tubes that compose this Alcyonium are connected to- 

 gether by minute reticulated fibres ; these enclose a stiff 

 gelatinous substance which seems to be the flesh of this com- 

 pound animal, and these fibres, with their enclosed con- 

 tents, to be the muscles; for by the excretion of these it assists 

 in opening or closing the stars on the surface, while the suckers 

 or polype-like figures are pushing themselves out in search of 

 food, or when they are retreating to secure themselves from 

 danger/' 



In 1816 Savigny clearly pointed out that the species 

 Alcyonium digitatum, A. exos, and A. arborea, in the 

 possession of eight pinnate tentacles, must not be classed with 

 the Ascidians, the anatomy of which he described in some 

 detail. Alcyonium exos was probably the Alcyonium 

 palmatum of the Mediterranean, and Alcyonium arborea 

 the Paragorgia of Norway. 



In Cuvier's ' Kegne Animale' it is stated that in Alcyonium, 

 as in the Pennatuleae, we observe polyps with eight denticu- 

 lated tentacles, and a stomach prolonged into the ovaries; but 

 the first detailed description of an Alcyonid was that given by 

 Milne Edwards in 1835 (9). 



This distinguished naturalist obtained some specimens of 

 Paralcyonium (?), to which he applied the generic name 

 " Alcyonide," at Cape Matifou, in Algeria, and he gave to the 

 Academie des Sciences a description of the anatomy, which, 

 considering the simplicity of his methods, is remarkably accu- 

 rate and detailed. He pointed out the individuality of the 

 polyps, and that each of them is capable of independent 

 action, although acting in response to stimuli with its 

 neighbours. He cut off a single polyp, opened it longitudi- 

 nally, and discovered the stomodseum, with its free opening 

 into the coelenteron, the eight mesenteries with their attach- 

 ments, the ovaries, and the cavities in the tentacles. With 

 regard to the structure of the colony, he pointed out that tubes 

 (loges) running down into the colony are really the continua- 

 tion of the polyps, " II suffit d'uu examen superficiel pour se 



