8 Mr. J. J. Quelch on some 



the figures given, can hardly be separated from Flumularia^ 

 since in all essential features the two genera seem to be iden- 

 tical, with but the slight exception that the single pinna 

 borne by each joint occasionally departs in Antennopsis from 

 the ordinary distichous alternate arrangement. This condi- 

 tion seen in the dried state of the present species entirely 

 disappears when the specimen is placed in water ; the torsion 

 of the stem becomes lost and the specimen assumes the normal 

 pinnate habit. 



In many of its characters this species recalls P. antennata 

 and P. megalocepJiala. 



Plumularia delicatula^ n. sp. (PI. II. fig. 3.) 



Hydrocaulus attaining a height of more than 100 millim., 

 simple, not fascicled, very distinctly jointed, of very variable 

 thickness in different specimens, and often quite slender, 

 rather wiry, arising from a mass of tubular filaments. Pinn« 

 alternate, one on each internode, very thin and delicate, 

 attached to a rather short process of the stem, which is 

 scarcely or not at all swollen at the base ; regularly jointed 

 with oblique joints ; alternate internodes bearing hydrothecas 

 and rather elongated, being nearly twice the length of the 

 intervening internodes, which are about four times as long as 

 they are broad ; each internode more or less marked by slight 

 annular constriction at their extremities, chiefly noticeable on 

 the proximal internode of the pinna. Hydrothecse rather 

 deeper than their width, which is about twice the general 

 diameter of the internodes. Neraatophores numerous, two at 

 t])e lateral margins of the hydrotheca and one at its proximal 

 side, one on the intervening internode, one or two on the 

 internode which is attached to the process of the stem ; one 

 on each side of the base of this process, and two placed singly 

 along the stem on each internode in a line above the process 

 of the internode below. 



Gonothec93 borne in the axils of the pinnae, flask-shaped, 

 elongated^ with a short neck. 



The delicate pinnce in this species are often broken ofl" in 

 dried specimens, when but a rather wiry stem is left. Its 

 closest ally seems to be Plumularia setacea, from which it 

 differs in the nature of the joints, in the relative length 

 and thickness of the internodes, and in the disposition of 

 the nematophores on the stem and on its processes. 



Antennularia irregularis^ n. sp. (PI. 11. fig. 4.) 

 Hydrocaulus simple, jointed, slightly thickened, attaining a 



