46 THE OCEANIC HYDROZOA. 



The anterior facet is prolonged into an obtuse process, which carries the nectocalycine 

 duct, and by which therefore it is attached to the coenosarc. This facet is excavated anteriorly 

 by the superior aperture of the hydroecial canal, over which the lower aperture of the hydrce- 

 cium of the proximal nectocalyx fits. 



The hydrophyllium has a very remarkable form (fig. 1 c). It consists of a central thick median 

 part, produced into two thin and flat lateral alse. The former has a slightly concave anterior 

 margin (towards the coenosarc), and a flattened upper surface, which forms nearly a right 

 angle with its posterior contour. From the middle of the upper surface a small recurved pro- 

 cess arises. Another is developed at the junction of the upper and posterior contours, and a 

 third arises about the middle of the posterior edge. About the middle of the upper edge of 

 each ala a similar process arises. The lower edges of the alse are truncated, and produced 

 into a sharp recurved point where they meet the anterior edges. 



The phyllocyst presents a globose superior division, passing below into a long caecum. 



Length of the proximal nectocalyx . . j inch. 



Breadth „ „ 



Length of tlie distal nectocalyx 



Breadth „ „ 



Hydrophyllium 



jt 



3 )) 



1 

 50 JJ 



The specimens on which this description is founded were taken in great abundance on the 

 23d of June, 1847, during a beautifully calm and moonlight night, while the ship was passing 

 within a few miles of the southern shore of Tasmania. The edges of the larger specimens 

 were all coloured deep blue. I obtained .-^(^ya Bassensis again in Bass's Straits in 1848; 

 and I took a young specimen in the South Pacific, May 15th, 1850. 



Quoy and Gaimard ('Astrolabe,' t. iv, p. 91) give an account of a Biphjes Bassemis 

 which they discovered at the entrance of Bass's Straits, and which, I have no doubt, notwith- 

 standing the brevity and insufiiciency of their description, and the imperfection of their figures 

 (' Zoophytes,' pi. iv, figs. 18, 19, 20), is that here described. Their specimens measured from 

 eight to ten lines in length. The species has not to my knowledge been described since. I 

 suspect that my Splienoides australis is the Diphyozooid of this species. 



Abyla Vogtii (n. sp). PL II, fig. 3. 



The proximal nectocalyx has five faces arranged around its vertical axis. Of these the 

 posterior is pentagonal, and larger than any of the others, its superior angle forming the apex 

 of the organ. Two supero-lateral four-sided faces shelve away from a median superior 

 ridge, as in the foregoing species ; and there are likewise two infero-lateral four-sided faces. 

 But the anterior pentagonal face is replaced by two quadrilateral faces, which unite to 

 form a median longitudinal ridge. The inferior face is consequently pentagonal. 



The posterior face is deeply emarginate below, where it forms the wall of the hydroecium, 

 and the edges of the emargination are strongly serrated. The inferior margin of the infero- 

 lateral face is also serrated, and appears deeply notched, from the fact that its posterior part is 

 produced to form the lateral wall of the hydrcecium. From the outer surface of this wall, on 



