1861.] 



SPECIES OF ACANTHOGORGIA. 



297 



times nine) large erect spicula project round the orifice of each cell 

 at eight angles, corresponding with the same number of shghtly ele- 

 vated ribs or crests on the outside of the cell formed by other spi- 

 cula ; the exposed portion of these projecting oral spicula is smooth. 

 In A. hirsuta the exposed portions of the corresponding spicula are 



Acanthogorgia grayi. 



rough. The orifice itself in a dry specimen is covered in by another 

 series of large spicula, sixteen in number, arranged in eight pairs, 

 the apices of which meet in the middle. At the outside of the cells 

 the spicula are placed parallel, not crossed as in A. hirsuta. 



The spicula are composed of calcareous matter, and are at once 

 dissolved with effervescence on the application of a strong acid, 

 leaving behind a formless mass of brown animal matter. The spicula 

 which he in the bark between the cells are fusiform, slightly bent, 

 and for the most part very stout, some elongated, others contracted 

 to an ovoid form ; those which project round the orifices of the cells 

 have their basal portion geniculate, flattened, and very rough, with 

 protuberances ; and not unfrequently the bases are branched. The 

 spicula of both species are pretty objects under an object-glass of 

 low power. 



Acanthogorgia grayi differs from A. hirsuta (of which a figure is 



Acanthogorgia hirsuta. 



here given for comparison) in the much smaller size and in the form of 

 the cells, which are cylindrical, not bell-shaped nor contracted at the 



