REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 59 



related to C. hbhmii and C. micramphidiscoides, which together form 

 a rather defined group of this genus, so far as the skeletal components 

 are concerned. However, C. bohmii differs from the species discussed 

 in possessing characteristic microscleres, and C. micramphidiscoides 

 is recorded as possessing two distinct series of microscleres, one of 

 them sharply pointed amphioxea. Even though it is possible that 

 future research may demonstrate that such acerate microscleres are 

 adventitious and belong to the spicular components of another 

 genus, it is best to retain the separate specific status of C. scabrispiculis 

 until additional data become available. A future revision cannot 

 rest mth the study of this apparently well-defined group alone, 

 but uill have to deal with the entire genus, all species of which are 

 in urgent need of a comprehensive review. 



Corvospongilla ultima (Annandale, 1910) 



Plate 4, FiGUEES 12, 13 



Spongilla ultima Annandale, 1910c, p. 31; 1911c, p. 104; 1912b, p. 99. 

 Corvospongilla ultima Annandale, 1912d, p. 384; 1918a, p. 213. — Gee, 1931e, 



p. 51; 1932c, p. 27.— Penney, 1960, p. 38. 

 Corvospongilla ultima var. spinosa Annandale, 1912d, p. 390. — Gee, 1931e, p. 49; 



1932c, p. 27.— Penney, 1960, p. 38. 



Material. — Syntype of S. ultima (AusM. Reg. no. Z 851), slides 

 of type of C. ultima var. spinosa (IM and N. Gist Gee no. 54606). 



Description. — Sponge forming thin crusts on sohd supports; 

 surface sUghtly rough to distinctly spiny, oscula small but conspicuous. 

 Skeleton forming a compact but somewhat irregular reticulation, 

 amount of joining spongin considerable. Consistency of hve sponge 

 hard. 



Megascleres almost straight to feebly curved stout amphioxea, 

 entirely smooth; length range 200-255 fj., mdth range 16-20 /x. 



Microscleres apparently rare in symplasm; represented by micro- 

 bu'otulates with a smooth, only feebly curved shaft, terminal spines 

 relatively short but distinctly incurved; length range 24-40 n, diameter 

 of rotules 4-9 /x. 



Gemmoscleres usually slightly to moderately curved and stout 

 amphistrongyla, irregularly spiny, and of greatly varying lengths; 

 length range 33-70 fi, \\ddth range 8-15 /x. 



Gemmules usually adhering to substratum, but often a number of 

 free gemmules also present in inner symplasm; they are spherical, 

 large, ranging from 400 /x (free) to almost 900 /j. (adhering) in diameter; 

 pneumatic coat feebly developed and without discernible air spaces; 

 gemmoscleres present in two distinct layers, not separated from each 

 other by an empty space; inner layer resting on inner gemmular 

 membrane, outer enclosed in the strong basal membrane of the sponge; 



279-130—68 5 



