The Sponges of Leake Biwa. 7 



definite skeletal cages, and S. aspinosa, therefore, appears to be 

 quite a distinct species. 



Owing to the absence of gemmule-spicules it is impossible to 

 assign this species definitely to any existing subgenus, but its close 

 relationship to S. lacustris leaves little doubt that the two are sub- 

 generically identical. It is related to 8. sinensis Ahn. 1 ' from Su- 

 chau, which may ultimately prove to be identical with it. 



S. aspinosa was originally described from the United States of 

 North America and has not as .yet (unless S. sinensis be identical) 

 been described in any other country but Japan. We have examined 

 a single specimen from L. Biwa near the Biological Station 

 at Otsu. 



Subgenus Stratospongilla, Ahhandale. 



The number of the species as yet attributed to this subgenus 

 is still relatively small and most of these can be readily diagnosed. 

 The one species that occurs in L. Biwa is however, remarkable for 

 its variability. 



Spongilla element is AhNAHDALE. 



PL I, figs 5-8, PI. II, fig. 2. 



1909, .S'. dementis, Annandale, Proc. U. S. Nat. Mus. XXXVI, p. 631. 



1910, S. yunnanensis, id., Rec. Ind. Mus. V, p. 197. 



Three phases of the species may be distinguished, so far as the 

 external characters are concerned, viz. — 



Phase I. (PI. I, fig. 5). In this phase the sponge forms a flat 

 crust of lichenoid outline and as a rule less than 10 mm. thick. 

 The colour may be leaf green, greyish or yellowish. The oscula 

 are numerous and lie scattered on the surface irregularly. Their 

 size is moderate (not more than 1.5 mm. in diameter) and their 

 outline is not very regular; often one horizontal axis is considerably 

 longer than the other at right angles to it. There is sometimes a 

 hollow nodule or cowl at one side of an osculum which has the 

 appearance of protecting it in one direction. Relatively large 



1) Proc. U. S. Nat. Mus. XXXVIII, p. 183 (1910). 



