84 W. M. Bale: 



Orfhopj/xis. Probably these may be bilateral to the same extent 

 as those of Orf/iopi/.ris: in any case they seem to form a distinct 

 link hetAveen the two genera. 



As stated under 0. comparivlaria Von Lendcnfeld included under 

 that species two distinct hydroids, an OrfJiopi/xu. and a Silicularia^ 

 the latter of which is here distinguished under the name of .S'. 

 rawpannJaria. 



In considering the relations of OrfJ/op//,vis and Silicularia 

 we must not overlook the different structure of the hydranths. Those 

 of Orthopyxls are, so far as an ordinary examination can disclose. 

 purely radial, while some species at least of Hilicninria are dis- 

 tinctly bilateral, as described by Hilgendorf in his //. nsipnmetrica , 

 and as they exist in Von Lendenfeld's specimens, and ai-e indicated 

 by Hartlaub in E. reticulata. A large lobe or inflation occupies 

 that side of the hydrotheca, which is lower than the rest, apparently 

 to accommodate it, and as all species of Silicularia (except S. diver- 

 yens), also have one side lower, it is presumable that the structure' 

 of the hydranth is similar in all of them. Another peculiarity in 

 our specimens is the union of the proximal part of the tentacles 

 in a sort of calyx with an annular, thickened border, and of this 

 also there is a distinct indication in Hartlaul>'s figure of E. 

 reticulata. 



Silicularia campanularia (Von Lendenfeld). (PI. XIII., 

 Figs. 1-6). 



Eucopella cainjian iilaria, in part. Von Lendenfeld, Zeitschr, 

 f. wiss. Zool.. v.. 188:^, p. 497-583; pi. xxix., fig. 15, Dl. 



Eucopella campanularia. Bale, Proc. Lin. Soc. N.S.W., (2), 

 iii., 1888, pi. xiii., figs. 9-15. Mulder and Trebilcock. 

 Geelong Naturalist, (2), vi., 1914, p. 9, pi. ii., figs. 

 8-11. 

 1 Eucopella reticulata, Hartlaub, Zool. Jahrb. , Suppl. vi.,. 

 iii.. 1905. p. 569, fig. lU. 

 Hydi'orhiza very broad and thick-walled. Avith numerous branches, 

 which are mostly given oft' at liglit angles, and are commonly oppo- 

 sirL'. IVduncles very stout, and with thick perisarc, the longer 

 (UK'S sometimes a little attenuated in the middle, rounded at the 

 top, and narrowed in at the base, one or tAvo rounded or oblong 

 segments sometimes at the top, a distinct rounded or angular bead 

 betAvecn the nednmle and the hvdrotheca. 



