338 A MONOGRAPH OF THE AUSTRALIAN SPONGES, 



one might say, codified knowledge, now is added the experience 

 gained by the investigation of the rich and previously unknown 

 Australian Sponge fauna. 



In the systematic part of this Monograph the following classifi- 

 cation shall be adopted. The reasons which have induced me to 

 adopt this system shall be expounded anon, under the headings of 

 the different groups. 



SPONGI^E. 



CCELENTERATA, WITH A GASTROVASCULAR SYSTEM WHICH 

 OPENS ON THE SURFACE WITH MANY SMALL AND ONE OR 

 A FEW LARGE APERTURES. NOURISHING MATERIAL FLOWS 

 IN THROUGH THE SMALL PORES, THE LARGE PORES OR 

 OSCULA ARE CLOAOE. FRILLED CILIATED CELLS ARE GENER- 

 ALLY AMASSED IN CERTAIN PORTIONS OF THE CANAL 

 SYSTEM. ALL THE EPITHELIA CONSIST OF SINGLE LAYERS 

 OF CELLS, THE MESODERM IS ALWAYS HIGHLY DEVELOPED. 



1. ORDO CALCISPONGI^E. 



SPONGI/E POSSESSING A SKELETON COMPOSED OF CARBO- 

 NATE OF LIME WITH A LITTLE ORGANIC SUBSTANCE, GAS- 

 TRULA FORMED BY INVAGINATION. 



1. FAMILY ASCONID^E. 



Calcispongiae consisting of a thin walled porous sac. 



2. FAMILY SYCONID^E. 



Calcispongice with a thick wall, traversed by radial tubes (canals). 



