rS - THE OCEANIC HYDROZOA. 



Fam. STEPHANOMIADiE.' 



Genus STEPHANOMIA {Peron and Lesuewr). 



Nectocalyces and pneumatophore unknown. Tentacula with lateral branches terminated 

 by an involucrate sacculus with a single filament. 



Stephanomia Amphitridis. pi. VII. 



On the 4th of May, 1848, during a calm which had already lasted some days, I saw 

 from the deck, floating at the surface of the sea near the ship, the beautiful organism a 

 part of which is figured of the natural size in Plate II, fig. 1. I threw the towing net over it, 

 and succeeded in capturing it and transferring it, apparently uninjured, to a basin of sea- water, 

 where it remained entire all that day ; by the next morning, however, all the hydrophyllia had 

 become detached though the polypites remained perfectly lively. I did not perceive 

 any motion in the individual hydrophyllia, but when the living mass was irritated, either by 

 the least touch or even by pinching one of the depending tentacles, the ccenosarc 

 shortened, and thus brought them into close contact. The ordinary position was horizontal, 

 with the tentacles hanging down in the water, and when I first saw the animal it was 

 curved to one side. 



The hydrophyllia were perfectly colourless, and so transparent as to be almost 

 imperceptible when in the water ; the coenosarc had a whitish hue ; the enlarged portion 

 of the polypites was pink or scarlet. The reproductive organs were colourless, as were 

 the stems and lateral branches and filaments of the tentacles, while the tentacular sacs 

 were scarlet. 



The body bore handling very well, and a piece could be cut off from one end without 

 causing any detachment of other parts. 



The coenosarc had a diameter of about one twentieth of an inch, with thick, muscular 

 walls. It was obviously broken at each end. 



The hydrophyllia surrounded the ccenosarc in whorls of four (figs. 2, 3) ; they were 

 attached by triangular, striated processes of the ectoderm, whose base was inserted upon a 

 triangular ridge, which traversed the middle of the internal face of each hydrophyllium 

 (fig. 4). From this a clear linear canal is continued almost to the extremity of the organ. 

 The hydrophyllia were in general leaf-shaped, and it appeared to me that a distinction might 

 be drawn between those which were situated at the sides and those which were* superior and 

 inferior ; the latter (fig. 5, 5 a) being distinguished by a sort of shoulder on one side of their 

 upper extremity, which is absent in the lateral hydrophyllia (figs. 6, 6 «, 6 b). 



' I commence with this genus because I have bad no opportunity of examining any Apolemia, 

 Halistemma, or Forskdlia. 



