^g Art. 1. - N. Aunaiidalo and T. Kawamura : 



absent from them, but a great part of the marginal region, to 

 a depth of at least 150 feet in places, has a bottom of very fine 

 gravel and coarse white sand, which does not support more than a 

 scanty growth of weed. In both " lakes " there are places where 

 the margin is stony. 



The sponge-fauna of the two "lakes" differs considerably, 

 though there is probably no species confined to either. Generally 

 speaking, that of the South Lake is much the richer, Spongilla 

 lacustris, S. semispongilla and Ephydatia midier I var. japonica being 

 the most abundant forms. S. dementis, on the other hand, is 

 characteristic of the North Lake; it is only found in very pure 

 water and avoids positions liable to complete or partial dessication. 



It is probable that all the species in the fauna except S. 

 dementis can live in water from 2 feet to at least 20 feet deep, but 

 they are most abundant, in the cases in which they are abundant 

 at all, in less than 10 feet of water. S. dementis usually lives at 

 depth of from about 6 to about 150 feet, but has been found on 

 Seta railway bridge and in the Kyoto water-works near the surface. 



8. fragilis is most usually found attached to sticks and twigs 

 that have fallen into the water or to the stem of reeds, but it also 

 occurs on stones. In a small lake communicating with the main 

 body of water at Komatsu on the western side, it is particularly 

 common on reeds, often growing together with S. lacustris. The 

 latter sponge is, however, perhaps most often found on stones near 

 the edge and on the piers of landing-stages, particularly at the south 

 end of L. Biwa. S. semispongilla grows both on stones and lightly 

 attached to weeds that sway freely in the water, such as JYitella, 

 Myriophyllum, etc. E. midleri var. japonica occurs on stones, on 

 dead bamboos and on other bodies that afford a smooth surface of 

 some area. S. dementis spreads itself on the piers of landing-stages 

 and the pillars of bridges, whether they be of wood or stone, and 

 in its massive form is attached to the shells of molluscs and to 

 small pebbles. 



In some cases a definite correlation can be established between 

 the nature of the object to which the sponge is attached and its 

 external form, though in most species the general appearance of 



