JOURNAL OF THE COLLEGE OF SCIENCE, TOKYO IMPERIAL UNIVERSITY. 



VOL. XXXIX., ARTICLE 1. 



The Sponges of Lake Biwa. 



By 



Nelson ANNANDALE, V. Sc. 



Indian Museum, Calcutta, 



and 



Tamiji KAWAMURA, Rigakushi, 



Biological Station, Otsu. 



{With two Plates.) 



It is evident that conditions are unusually favourable for the 

 growth of the Spongillidae in Lake Biwa, in which the sponges are 

 found mainly in the form of encrustations, often of considerable 

 area, on the pillars of piers and bridges, as smaller ramifying 

 masses attached to water-weeds and stones, as elliptical growths on 

 the shells of molluscs and on pebbles, and even in the form of free 

 spheres lying on a sandy bottom. In collections from the lake 

 made in 1914 and 1915 we are able to distinguish seven species, 

 namely : — 



Spongilla (Euspongilla) lacustris auct. 



Spongilla {Euspongilla) semispongilla (Annandale). 



Spongilla (f Eu spongilla) asptinosa Potts. 



Spongilla {Stratospongilla) dementis Annandale. 



Spongilla (Eunapius) fragilis Leidy. 



Ephydatia mülleri var. japonica (Hilgendorf). 



Heteromeyenia kawamurae Annandale, sp. nov. 



The only other freshwater sponge as yet found in Japan is the 

 typical form of Ephydatia mïdleri (Liebe.). 



I. Systematic. 

 Key to the Japanese Spongillidae. 



I. Gemmule-spicules, if present, without transverse disks at the 

 extremities [Genus Spongilla] 



