812 SYDNEY J. HICKSON. 



branching, thin coenenchyni, and similar spicules, and Melitodes rubeola (W. and S.) from the 

 Arafura Sea which shows a similar colour pattern, pink nodes with white internodes, to that 

 of some of the varieties of our species, but it differs from the former in the colour pattern, and 

 from the latter in its mode of branching. The species may be described as "A delicate 

 species branching in all planes with frequent anastomoses. Colour very variable ; but the colour 

 of the nodes and internodes frequently different." 



Family Muriceidae, Verrill. 



This large family is well represented in the collection. The characters are ill-defined, and 

 it might be fairly maintained that such genera as Muricella and Elasmogorgia would be more 

 correctly placed in the family Gorgoniidae. The genera represented in the family are Acantho- 

 gorgia, Behryce, Acamptogorgia, Elasmogorgia, Muricella and Acis. 



Acanthogorgia jlahellum n. sp. (figs. 1 and 2). 

 Locality. Addu Atoll to seaward of atoll reef, 25 fathoms. 



The specimens of this species are in three pieces, and possibly they all belonged to one 

 colony. 



The largest piece retains the main stem and a portion of the disc of attachment. It is 

 140 mm. in height and 140 mm. in width. The main stem is 2'5 mm. in diameter just above 

 the disc of attachment, and the branches of the flabellum are on an average 1 mm. in diameter. 



The branching is entirely in one plane and the branches anastomose freely to form a 

 reticulate flabellum with meshes about 15 mm. from angle to angle. The coenenchym is very 

 thin and the surface is rough, being beset with numerous regularly arranged tuberculate warts. 

 The anthocodiae are cylindrical, 0-5 — 1 mm. in length, with slightly projecting spines at the 

 free edge. They are numerous and crowded on most parts of the flabellum, and situated 

 principally in the plane of the flabellum. Young zooids are interposed between the full-grown 

 ones. The colour of the coenenchym and anthocodiae is white. 



The axis is black in the older parts, brown in the younger. The axis is homy, but contains 

 a core of bead-like calcareous bodies in definite chambers as in Acamptogorgia spinosa (Hiles 10). 

 The spicules are colourless and very variable in shape. The spicules of the superficies of the 

 coenenchym are so firmly interlocked and fused that they cannot be separated without injury. 

 They are irregular tuberculated foliaceous clubs and branched spindles. In the anthocodiae a 

 number of slightly bent spindles, fi-om 2 — 3 mm. in length, are found. These are peculiar 

 in that one half of their length is usually smooth and the other half tuberculated. At the 

 free edge a few very long 0^5 mm. dagger-shaped spicules are found. In addition to these a 

 number of very irregular foliaceous spicules occur both in the anthocodiae and coenenchym. 



This new species is the first species of the genus to be found in the Indian Ocean. The 

 other species occur in the Atlantic and Pacific Oceans. 



Some species of the genus branch in one plane only and anastomoses of the branches 

 are recorded in some of these (A. inermis Hedlund, 6 ; A. schrammi, D. and M., 2), but the 

 formation of a reticulate flabellum such as we find in this species is unusual. The anthocodiae 

 are distinctly smaller than usual. In several species described by Studer (20) they range fi-om 

 1 — 2 mm. in A. truncata, to 4 — 8 mm. in A. verrilli. In this species they are rarely over, and 



