64 THE OCEANIC HYDROZOA. 



Amphiroa alata {Jjesueuf). PI. V, fig. 1. 



The hydrophyllium is depressed and broad, with six unequal faces ; the superior face is 

 a little convex and four-sided ; its anterior side is convex and very much longer than 

 the posterior, which is straight; the lateral edges of this face are nearly straight. The 

 anterior face is a parallelogram, elongated, and convex from side to side. The lateral faces 

 are slightly concave and four-sided ; their inferior edges are concave and prolonged downwards 

 posteriorly. The posterior face is a vertically elongated parallelogram. The inferior face is 

 flat and four-sided posteriorly, but anterioriy it is obliquely truncated and occupied by a wide 

 aperture leading into a conical cavity, which extends beyond the centre of the organ vertically. 

 A very short, narrow duct runs from the apex of this cavity to just below the summit of a 

 great oval phyllocyst with vacuolated walls, which occupies almost all the space between the 

 posterior wall of the cavity and the posterior face of the hydrophyllium. From the upper 

 end of this there is given off on each side a long, slender ctecum, slightly concave upwards, 

 which ends close to the junction of the anterior and lateral faces. 



The gonocalyx is a prism of apparently four sides, but its lower face is surrounded 

 by five points like those in the nectocalyces of Abyla and Biphi/es, with which the organ 

 presented a further resemblance in the junction of two of tlie points by a strong, transverse 

 plate, and their continuity upwards with strong crests, between which a deep groove is 

 included. The upper end of the organ is pyramidal. 



Length of the hydrophyllium, one fourth of an inch. Length of the gonocalyx, one 

 fourth of an inch. 



Amphiroa alata occurred only in Torres Straits. 



In one specimen of this Diphyozooid (PI. V, fig. 1 h) obtained July 26th, 1849, I found 

 three reproductive calyces ; one was very small, the other two large and fully developed. 

 Of these, the larger contained an ovisac, in which were four or five large ova. The smaller 

 contained a sperm-sac, with incompletely developed spermatozoa. 



This is one of the species drawn and named by Lesueur, but first pubHshed by 

 De Blainville, in his 'Actinologie.' The description given in the latter work is very 

 imperfect, but the figure leaves no doubt in my mind as to the identity of Lesueur's species 

 with mine. 



I suspect this Amphiroa to be the Diphyozooid of Ahyla trigona ; at least, the hydro- 

 phyllium of the latter (PI. Ill, fig. 1 e) has the same general form and large oval phyllocyst, 

 with slender lateral processes. 



Amphiroa angulata. PI. V, fig. 2. 



The hydrophyllium has the same general form as in the foregoing species, but its 

 anterior face is concave instead of convex, and its upper edge is angulated in the centre, 

 while its lower edge is notched opposite the same point. Furthermore, the posterior wall of 



