26 Art. 1.— ^i". Annandale and T. Kawamura : 



finally over its lower surface, thus at last completely enclosing it, 

 We have noticed many specimens of Melania which still remained 

 alive and able to progress with some speed, although their shell 

 were completely covered and the living parts of the animal could 

 only be extended through a small aperture in the sponge. Molluscs 

 in this position moved with a curious jerky action, bearing a 

 sponge-mass several times as large as themselves. As in the case 

 of the Lamellibranchs, 'however, the mollusc is finally over- 

 whelmed. In both cases, the sponge, as the body of its host de- 

 cays, spreads out over the inner surface of the shell, doubtless 

 absorbing the decaying body as it does so. S. lacustris in L. Biwa 

 sometimes attaches itself to living individuals of Vivipara and 

 Melania and grows round them in the same way (PI. I, Fig. 3), 

 and a similar phenomenon has been observed in the case of both 

 of Spongillidae and of Suberitidae in India 1} and elsewhere. 



The free spherical specimens of S. dementis may originate in 

 one of the two ways: either they may have broken loose 

 from pebbles or shells, or they may have completely covered the 

 hard bodies to which they were originally attached. In the 

 former case the original point of attachment is indicated by a closer 

 reticulation of the superficial skeleton. We have found a perfectly 

 free spherical specimen, however, that was less than 1 cm. in dia- 

 meter, had no hard extraneous core and no such differentiation of 

 the skeleton, and it seems possible that the sponge may have been 

 free from a very early stage of growth. 



The largest specimen of S. dementis that we found attached to 

 molluscs were some that we took off Komatsu in November, 1915, 

 on the comparatively large shells of Anodonta calipygos. They 

 were intermediate in form between Phase II and III of the 

 species. With them w T e found similar specimens spreading ir- 

 regularly over a bottom of small stones. We have already noted 

 that at Seta the sponge occasionally attaches itself to Corbicula-shells 

 without being able to form more than a fine crust of small 

 dimensions. 



1) Annandale, Mem. Ind. Mus. V, p. 41 (1915). 



