76 Zoological Society. 
middle. It is composed of fibrous matter without spicula. Caustic 
alkali has little or no effect upon it, even on the application of heat. 
Bark composed almost entirely of spicula, studded with sessile cylin- 
drical cells, irregularly distributed on all sides. These cells have a 
height of from the thirtieth to the twentieth of an inch, and their 
diameter is about half the height. The upper halves of eight (some- 
times nine) large erect spicula project round the orifice of each cell 
at eight angles, corresponding with the same number of slightly 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 
rough. ‘lhe 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 lie 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 
here given for comparison) in the much smaller size and in the form of 
Miri Wh] )/f/4 
|) ll Wi) ‘5 
oy 1 // 
Acanthogorgia hirsuta. 
the cells, which are cylindrical, not bell-shaped or contracted at the 
bottom. In the only specimen of the former which I have seen, 
the cells are not nearly so numerous as in the specimens of the 
latter which have come under my notice. Moreover, the orifices of 
the cells in 4. hirsuta are not roofed in with spicula in the same 
complete and regular way as is the case with the cell-orifices of this 
species. Lastly, I have not noticed any branching at the bases of the 
large spicula of 4. hirsuta. 
The only specimen of this very curious Black Coral which has 
