788 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, 



represented as widely divergent, which was not the case with the 

 Museum specimens, and I have observed that the angle at which 

 branches spring from the stem usually varies but little within the 

 limits of a species. These specimens now appear to me identical 

 with A, phillipina, the hydrothecae and sarcothecae being exactly 

 similar to those of Mr. Brazier's specimens, and the hydrothecee 

 varying in the same directions, the branching, as nearly as I 

 could judge from the specimens, (which were fragmentary) being- 

 also similar. The only difference which I can find is in the 

 colour, which is somewhat darker, but this is partly due, both 

 in the original specimens, and in another of the same type 

 in the present collection, to a number of minute black specks 

 scattered irregularly over the interior of the polypary, and which 

 are probably not constant. On the whole, though the gonosome 

 is absent, I have little doubt that the specimens which I formerly 

 described as A. urens belong really to A. PMllipina. 



In Kirchenpauer's description no mention is made of the fact 

 that the gonothecse spring from modified hydrothecae, but 

 his figure shows this as the structure. He describes the 

 sarcothecae above the gonothecse as being in pairs decussately 

 arranged, but though they may present such an appearance in 

 certain aspects, most of them are really in threes, representing the 

 mesials and laterals of the suppressed hydrothecse. The first one 

 or two above the gonotheca, however, are borne at the side of the 

 nematocladia without any to correspond on the opposite side- 

 The gonothecse are supported on very long internodes, and the 

 contents of the proximal one ripen first ; in fact, I found in most 

 cases only one on the nematocladium, the first having ripened and 

 fallen off. Sometimes, however, only one is produced. The young 

 gonothecse are nearly circular in outline, with a broad marginal 

 wing, but those which are fully developed are ovate, with the 

 gonotheca larger and the wing narrower. The ring of granules 

 surrounding the sporosac is similar to those of Halicornaria 

 (Lytocarpus) saccaria, which has been described by Professor 

 Allman (Journal of the Linnean Society, Zoology, Vol. XII.). 



