74 W. M. Bale: 



A noteworthy characteristic of the genus is the wide range of 

 variation displayed in the forms of the gonangia. Every species 

 has its typical form, but a large proportion of the individual gon- 

 ;angia differ from their respective types very considerably, dis- 

 torted and irregular forms being abundant. Several species which 

 scarcely differ at all in regard to the trophosome have nevertheless 

 gonangia quite unlike each other. 



Only in 0. caliculata and Evcopelln campanularia have tlie 

 gonozooids been the subject of elaborate investigations, tlie foinier 

 by Agassiz and the latter by Von Lendenfeld. The most important 

 ■distinction is the presence in E . cainpanuloria of eiglit otocysts on 

 the umbi'ella-margin. So far as is known there is no noticea])le 

 difference in any of the species between the gonangia which contain 

 tlie male and the female medusae. 



Perhaps the most striking point about the genus is the exceed- 

 ingly close relationship existing between the various species. Ex- 

 cept for the difference in the peduncles, which distinguishes 0. com- 

 pressa and 0. angidnta from the other forms included here, their 

 trophosomes agree so closely that, keeping in mind the variations 

 which exist in each species (and which will most probably be found 

 on furthei' investigation to be even more extensive than I have 

 'described them from the few specimens at my disposal^, we would 

 not find it surprising if all these variations were to occur within 

 the limits of a single species. Yet the differences in the gonosomes 

 appear ample to justify their separation. It is to be borne in 

 mind, however, that most of these species are described from the 

 trophosomes and the gonangia only; in none of them except 0. cali- 

 culata and E. campanularia have the gonozooids themselves been 

 ".sufficiently investigated to render it certain that they come strictly 

 "vvithin the limits of the genus as it is described by Agassiz and Von 

 Lendenfeld. ^ 



•Okthopvxis caliculata (Hincks). (Pis. XI. and Xll., Fig. 1). 



(Jainpainilaria cdl'cii/dfa, Hincks, .Ann. .Mag. Xat. Hist. (2), 

 xi.. 185;}. p. 178, pi. v.. fig. 5. Allman, Proc. Roy. 

 Soc. Edin.. iv., 1862, p. 61, 64. Hincks. Brit. Hyd. 

 Zooph., 1868, p. 164, pi. xxxi., fig. 2-2d. Jiale. Proc. 

 Lin. Soc. N.S.W. (2), iii., 1888, p. 755, pi. xiii.. figs. 

 ^-^^. Schneider, Zool. Jahrb.. x.. 1897. p. 482. 

 Th..rnely. Zool. Uesults, Willey, iv., 1900, p. 454. Har- 

 ;gitt, Amer. Nat., xxxv.. 1901, p. 88.'}. fig. 18. Hartlaul), 



