Australian Hydroids. 345 



Not riumidaria hahi, Billaid, Arch, de Zool. exp. et. gen. 

 (5), viii., 1911, p. Ixiii., fig. 3. 



Hydiocaulus nionosiphonic, pinnate, about 8 mm. in height, 

 two or three indistinctly divided internodes at tlie base of the stem 

 without pinnae, the rest divided by oblique joints into short 

 internodes, each of which bears a hydrotheca and a hydrocladium. 

 Hydrocladia alternate, the lirst internode (or two internodes) very 

 ^hort, without appendages, the others alternately short and long, 

 only the latter bearing hydrothecae. 



Hydrothecae reflexed, a strong inflexion in front partly filled up 

 by perisarc externally, and extended into an intrathecal ridge 

 reaching half through the hydrotheca; aperture large, margin jDro- 

 duced into a long pointed peak in front, the sides elevated into two 

 broad convex lobes, back forming a smaller lobe, free, a small, 

 narroAv lobe behind each lateral sarcotheca. 



Sarcothecae bithalamic, canaliculate, one below each hydrotheca 

 and two lateral above, one at the back of each hydrotheca on the 

 pinnae, and two abreast in the corresponding position on the stem, 

 one midway between every two cladiate hydrothecae, on the inter- 

 mediate internode, and a few on the lower part of the stem; all 

 sarcothecae rigid, the laterals mounted on very long j^eduncles 

 which run up the sides of the hydrotheca nearly to the margin. 



Gonothecae — female, broad, pyriform, truncate a little above 

 the widest part, operculate, margin with a thickened band, about 

 three or four sarcothecae near the base; male, much smaller, ovate, 

 Avith one sarcotheca; both sexes on the same hydrocaulus, but the 

 female on the lower cladiate portion and the male higher up. 



Loc. — Bream Creek (Bartlett), Queenscliff (Mrs. Bartlett), Airey's 

 Inlet (Mulder). 



A remarkable species,^ possessing the extreme development of the 

 lateral peduncles which characterises the genus HalopteniR of 

 AUman, not generally accepted. The> lateral sarcothecae, which are 

 tstout and rigid, and entirely open on one side, are consequently 

 •elevated above the hydrotlieca. The fixed anterior sarcothecae are 

 strongly curved over towards the hydrothecae, as in P. huski, etc. 

 The internodes of the stem, in front view, have a more or less 

 fusiform shape. The intermediate internodes of the hydrocladia 

 are shortei* than 1 have seen them in any other species, and tlie 

 joints above them are very oblitpie. 



