70 Proceedings of the Royal Society of Victoria. 



Up to the present time sixtj'-tvvo species of thi.s group of 

 sponges have been described from Australian seas, chiefly by 

 HfBckel, von Lendenfeld, Polejaeff and Carter. Sixteen 

 new species are described in the present paper, which brings 

 the total number of Australian species of Calcarea Heterocoela 

 u[) to seventy-eight. In order to make the work as complete 

 as possible, I have decided to include, not onl}' descri[)tions 

 or notes of the forty-seven species which I have been able to 

 study for myself, but also references to those species which 

 1 have not seen, and thus to provide a complete Synopsis of 

 the Australian Calcarea Heterocoela. 



In or(ier to arrange the sjiecies satisfactorily, I have been 

 obliged to adopt a classification which has many new 

 features. This classification has not been arrived at hastily, 

 nor without careful consideration of the work of previous 

 writers. It is impossible to justify it fully in this place, 

 because it is based upon a minute study of anatomical 

 details and a careful consideration of historical questions of 

 y)riority in nomenclature into which I have not space to 

 enter. I intend, however, to publish a paper on the minute 

 anatomy and classification of the group in another place, in 

 which these questions will be fully discussed ; and, in the 

 meantime, I may perhaps point out that the classification 

 proposed is based upon tlie careful anatomical examination of 

 a very large number of species. 



It will be seen that more stress is laid upon the arrange- 

 ment of tiie skeleton than is usual at the present day, and 

 less upon the form and arrangement of the fiagellated 

 chambers, which I find to vary considerably, even within 

 the limits of a single species. This change certainly facili- 

 tates the identification of specimens, and will probably be 

 welcomed by those workers who have not at their disposal 

 the elaborate appliances required for the preparation of 

 stained microscopical sections. 



Polejaefi'* clearly showed that no hard and fast line could 

 be drawn between the Sycons and Leucons of Hfeckel. 'J'his 

 idea was followed up by von Lendenfeld, who has created a 

 special group, the iSylleibidai,-\- to include the intermediate 

 forms. This group, however, seems to me to be very arti- 

 ficial, as, judging from my own observations, it appears that 



* Keport ou the Calcarea of the Challenger Expedition. 



t See especially " Die Si^ougieu der Adria. I. Die Kalkscliwamme." 

 Zeitsclirift fiir WissenschaftlicheZoologie, Vol. 5H, 1891. 



