490 



A MONOGRAPH OF THE AUSTRALIAN SPONGES, 



This can best be explained by the adjoined tabular description : — 



(8a.) The apertures in the wall of 

 the sack are closed, and tlie secundary 

 Pseudogaster hereby becomes a true 

 Oscular tube. At the same time the 

 Pseudosculum is converted into a 

 true Osculum. (Dendrilla rosea, Ca- 

 cospongia Exemjihim termhms. ) 



(7a.) This folding results in the 

 formation of an irregular sack, not 

 quite closetl, however, with a Pseudo- 

 sculum. Into this sack, which is a 

 Pseudogaster, only the Oscula open. 

 Whereas the inhalent pores are found 

 in the outer surface only {Aphrodite 

 Nardorus) 



(7b.) This folding results in the 

 formation of an irregular system of 

 wide Lacunas, Pseudogaster, in the 

 surface of which no Oscula, but in- 

 halent Pores exclusively are met 

 (with. (Euspontjia and Hippo- 

 spongia.) 



(6.) This whole structure again folds itself and a secundary 

 Pseudogaster is formed thereby, in the surface of which inhalent 

 pores and Oscula are found {Aulena, Halme and Hcdmopsis.) 



(5.) The chambers become regular in shape and the wall of 

 the sack is folded so as to form an ordinary sponge. The 

 Pseudogaster is converted into an Oscular tube ; the Pseudo- 

 sculum into a true Osculum (Leuconidw, Teichonidiv.) 



(4.) A Pseudogaster is formed by the Sponge attaining the 

 shape of a closed sack, in the walls of which the irregular 

 chambers lie. Small pores lead into the chambers from 

 without. Their larger excretary pores, chamber Oscula open 

 into the Pseudogaster (Leucoims.) 



(3.) The individuals coalesce to form an irregular mass 

 imbedded in a Mesoderm. Inhalent and exhalent pores 

 leading direct into the chambers are scattered irregularly 

 over the surface. (Aidoplegma.) 



(2.) Sponges which consist of a colony of Olynthis, the 

 individuals of which retain their individuality and Oscula. 

 (Soleniscus.) 



(1.) The whole sponge consists of one single irregular 

 ciliated chamber, with inhalent pores in its simple wall, and 

 a chamber Osculum, which at the same time is the Osculum 

 of the sponge. (Olynthus.) 



