304 A MONOGRAPH OF THE AUSTRALIAN SPONGES, 



Pseudopores is also not so sharp as in Halme Nidus Vesparum, 

 but more rounded. The Pseudopores themselves consequently 

 appear from without as trumpet-shaped openings narrowing towards 

 the interior. They measure on the surface 8 mm., and in the 

 narrowest part a little below 5 mm. aci'oss. They are more or less 

 circular and divided from one another by bridges about 7 mm. 



wide. 



Structure. 



In its structure our species represents a marked peculiarity 

 in one respect only. We usually find that the wide inhalent 

 canals, which are simple open tubes in the two foregoing species, 

 are here pervaded by numerous fine membranes, similar in structure 

 to those which pervade the vestibule space in the genus Aulena. 

 These contain a great number of wandering amceboid cells, which 

 are highly colorable and present in sections a very remarkable 

 appearance, after Alum-Carmin staining. I believe that here in 

 the inhalent canals we may perhaps look for the digestive opera- 

 tions of this sponge. It seems that the digestive functions are 

 performed hy different parts of the inhalent system in different 

 sponges. I believe also to have seen in these perforated diaphragm- 

 membranes, cells which might be considered as sensitive and ganglia 

 cells. 



Geographical Distribution. 



South Coast of Australia, Port Phillip (Yon Lendenfeld) ; St. 

 Vincent's Gulf (Haacke). 



Bathymetrical Distribution. 



In shallow water. 



The St. Vincent Gulf specimens are larger than those from Port 

 Phillip. 



62 SPECIES. 



HALME MICROPORA, NOVA SPECIES. 



Shape and Size. 



This species is irregular globose with deep, rounded indentures, 

 which divide it into lobes of varying shape and extension. Only 



