754 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, 



level of the " floor," which is a little above the base, and situated 

 obliquely ; margin very slightly everted, not toothed, somewhat 

 uneven. 



"The gonophores have the ordinary elongate shape 



At the time of liberation the medusa is similar to a newly-born 

 0. geniculata" (Von Lendenfeld). 



Hob. Eist coast of N. Zealand, Larninarian Zone. 



Dr. von Lendenfeld says of this species : " The stem of this 

 Obelia is creeping, adnate to foreign bodies, to which it clings like 

 a hydrorhiza. The stem bears hydranths on very short annulated 

 stalks, and also a few very short branches with nearly sessile 

 hydrothecse. These creeping stems are short, and take their origin 

 from a distinct hydrorhiza, which differs from the creeping stem 

 by the much greater thickness of its perisarc, and by the numerous 

 anastomoses which cause it to attain a reteform appearance." 



I have not been able to verify this description, nor distinguish 

 the " creeping stems " from a true hydrorhiza, but in any case the 

 stems which bear the hydranths and short branches are not the 

 " creeping stems," but the erect shoots. Dr. von Lendenfeld refers 

 to this species (but apparently not with absolute certainty), an 

 adult medusa which he found in large numbers in Port Jackson. 

 The tentacles are said to be from 30 to 40, and the umbrella 

 always in a reverted position. This is not the case with the young 

 medusa3 which were obtained with the trophosome.* 



0. australis is somewhat coarser and more rigid than 0. angulosa. 

 It maybe distvguished from that species by the internodes of the 

 stem, which are not abruptly curved outwards at their origin, but 

 are more or less curved alternately in opposite directions through- 

 out their whole length, so that the stem is flexuous. The hydro- 

 thecse are less conical than those of 0. angulosa, without the 

 distinct constriction at the level of the floor, which is also nearer 

 the base of the cell, and rather more oblique. 



*On p. 920, Vol. IX., Dr. von Lendenfeld says, "I have described this 

 species from the polyp-colonies and the young larvae which I obtained in 

 Port Jackson." In the original description, however, the only locality men- 

 tioned is the East coast of New Zealand. 



