336 ^. ^^f- ^^*^^ • 



Opiiiodks AUSTRALis, 11. sp. (Plate XV J., Fiir. 1). 



Hvdrorhiza a network of stout tubes, becoming more or les* 

 fascicled; stem straight, polysiphonic, between one and two 

 inches in height, branches short, straight, monosiphonic, divided 

 into internodes by straight or very slightly oblique joints; eacli 

 internode supporting a hydrophore close to the top. 



Hydrophores (primary) alternate, seated on very short processes, 

 of the internodes, long, normally divided by a slight constriction 

 into two parts — a proximal, which is cylindrical, and a distal,, 

 which is slightly expanding, with a narrow limbus and a circlet 

 of bright points. Secondary hydrophores when present given off 

 laterally from the proximal portion of the primary one, a third 

 and fourth sometimes present, each springing in the same way from 

 its predecessor. 



Sarcothecae small vase-shaped cups, springing from the sides of 

 the primary hydrophores, or sometimes of the others. 



Hydranths stout, constricted below the crown, with about 24-26. 

 tentacles. 



Gonangia barrel-shaped or nearly cylindrical above, tapering 

 below; summit broad and flat; borne on the hydrorhiza. 



Loc. — Port Phillip Heads (Mr. J. Bracebridge Wilson), Greens 

 Point, Port Jackson (Australian Museum). 



The stems originate as small monosiphonic shoots, bearing hydro- 

 phores, but soon become polysiphonic by the addition of supple- 

 mentary tubes which grow upwards from the hydrorhiza; sometimes- 

 also these tubes run for a short distance along the proximal parts- 

 of the branches. Ihe latter may spring from the supplementary 

 as well aa from the primary stem-tubes. 



In some cases the hydranths may be single, but more commonlr 

 they are borne two by two, each primary hydrophore giving origin 

 to a secondary one from the side near the base, and both support- 

 ing hydranths at the same time. Less often three and four may 

 be produced, each from the preceding one; this occurred on the 

 older parts of a shoot. The hydrophores themselves are of the 

 type usual in the family, but I saw no instance of the regenera- 

 tion-growth so characteristic of most of the species. 



Sarcothecae were not numerous, and did not occur with any^ 

 regularity, most of the hydrophores not being provided with them. 



