46 THE VOYAGE OF H.M.S. CHALLENGER. 



branch comes into contact with the horny joint of the stem, and then appears to arise 

 from the latter. The longitudinal furrows on the calcareous joints are deep and bounded 

 by sharp ribs, which have serrated edges. On the smaller branches the distance between 

 the individual teeth reaches 0"12 mm., and they project 0'04 mm. above the edge. 



The spicules of the ccenenchyma consist of a deep kyer of spiny spindles, which 

 follow the longitudinal canals in the furrows, 0"2 to 0*21 mm. in leugth, and 0*02 to 

 0'03 mm. in diameter ; and a superficial layer of flat, often slightly curved, spiny bodies, 

 whose edges interlock, and which cover the ccenenchyma thickly. They are prolonged up 

 the wall of the polyp in which they are placed peripherally from its base upwards. Their 

 form closely resembles that of the spicules of Mopsea. The upper edge is convex, 

 strongly toothed, the lower edge somewhat concave, with projecting, finely toothed lobes, 

 the surface spiny. 



Spicides of the ccenenchyma, length to breadth in mm. — 0"16-0'05 ; 0*15-0*05; 

 O-15-0-06. Thespiculesof the polyps measure 0-06-0-16; 0-05-0-18 ; 0-07-0-22 ; 0-07- 

 0'25 mm. The spicules of the ccenenchyma and of the polyp-wall are coral red. The 

 spicules of the tentacles are shaped like those of the polyp-wall, only somewhat more 

 slender and a little more spiny on the surface ; their colour is white. Height to 

 breadth, 0"05-0'12 ; 0"05-0'13 mm. The colour of the whole colony is a brick-red, the 

 polyp mouths white. 



Habitat. — Port Jackson ; depth, 30 to 35 fathoms. 



Family III. Primnoid^, Valenciennes {s. str.). 



Primnoacex (pars) Valenciennes, Comptes rendus, 1855, t. xli. p. 7. 



Priinnoacex {pars), H. Milne-Edwards, Hist. Nat. des Coralliaires, t. i. p. 138, 1857. 



Primnoadee, Gray, Proc. Zool. Soc. Lond., 1857, p. 285; ojh cit., 1859, p. 483. 



Primnoacex {pars) (as a division of Subfamily Gorgoninae), Kolliker, Icones Histiol., Abth. 2, 



1865, p. 135. 

 Primnoidx {pars), Ven'ill, Rev. Polyps East Coast N. Amer., Mem. Bost. Soc. Nat. Hist., vol. i., 



1884, p. 8; Trans. Conn. Acad., vol. i., 1869, p. 418. 

 Primnoadx {pars) + Calligorgiadx {pars) + Calyptrophoridx, Gray, Cat. Lithophytes Brit. Mus., 



1870, pp. 43, 34, 41. 

 Primnoadx (Subfamily), Studer, Monatsber. k. d. preuss. Akad. d. Wiss. Berlin, 1878, p. 641. 

 Primnoidx {emend.), Verrill, Bull. Mus. Comp. Zobl., vol. xi. p. 28, 1883. 



When Milne-Edwards, following in the steps of Valenciennes, established the family 

 Pliinnoaceae, for that group of Gorgonids in which the sclerenchyma was much more 

 developed on the bodies of the polyps than on the axis, and in which the polyps were 

 prominent, he adds — " Mais cette disposition n'appartient pas seulement aux Primnoac^es 

 et se retrouve chez plusieurs Gorgoniacees, notamment chez les Eunicees ; et ce qui 

 distingue essentiellement ces deux ageles entre eux, c'est la structure du sclerenchyme 



