REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 101 



terminally mth flat rotules of unequal diameter; faces of rotules 

 invariably strongly granular, arrangement of granules more or less 

 radial; margin of rotules irregularly crenulated or incised, often 

 bearing a number of discernible teeth separated by varying distances; 

 length differences of birotulates very pronounced: length range of 

 larger series 64-84 n, of smaller 32-48 /x; width range of lower rotule 

 19-22 n, of upper 17-20 /x; thickness of shaft 4-6 /i. 



Gemmules extremely abundant in mature sponge, scattered through- 

 out skeletal mesh work; in younger sponges necessarily confined to 

 basal parts; they are large and spherical, ranging in diameter 490-585 

 n; pneumatic layer very thick and irregvdar but rarely higher than 

 the longest gemmoscleres, consisting of minute air spaces; gemmo- 

 scleres embedded in this coat with their larger rotules firmly inserted 

 in the inner gemmular membrane; outer parts of pneumatic layer 

 occasionally reinforced by a small number of apparently adventitious 

 megascleres; outer gemmular membrane distinctly corrugated, and 

 almost white; foramen simple or bearing a very shallow peripheral 

 collar. 



Distribution. — Widely distributed in eastern Australia, rarely 

 penetrating the Dividing Range westward. 



Color in life. — ^Light tan to brown, typically of flesh color. 



Discussion. — Weltner's (1895) original description and his further 

 notes on additional material (1900) were based on incompletely 

 developed specimens. When fully mature, specimens of H. multi- 

 dentata always form large bulbous growths, and its gemmules are 

 extremely abundant and freely scattered through the skeletal mesh- 

 work. With respect to its spicular components this species displays 

 discernible variations. The form of gemmoscleres used by Traxler 

 (1896b) for the erection of his Ephydatia lendenfeldi can be found in 

 any range of specimens of H. multidentata from distant localities, and 

 Traxler's specific name therefore must now be considered synonymous. 



The spicular components of Spongilla lacustris var. sphaerica, the 

 true identity of which remained doubtful until the present, were found 

 during our studies to be identical with those of H. multidentata in all 

 respects, and the relegation of Lendenfeld's variety to a synonjrm of 

 Weltner's species is now possible. This procedure finally eliminates S. 

 lacustris, erroneously recorded for the Southern Hemisphere, from the 

 list of AustraUan species. 



The distribution of H. multidentata seems to be confined to the east- 

 ern watershed of the Australian Great Divide, its place on the western 

 slopes and in the interior of the eastern states taken by a closely 

 related but distinctly separable species, which will be described in a 

 forthcoming paper (Racek, MS.). 



