GEOGRAPHICAL DISTRIBUTION.--This sponge was originally described from North America (in which continent it is widely distributed) and has been recorded from the west of Ireland with some doubt. In India and Burma it is widely distributed. BENGAL, Calcutta and neighbourhood (_Annandale_); Sonarpur, Gangetic delta (_Annandale_); BOMBAY PRESIDENCY, Igatpuri Lake, W. Ghats (altitude _ca._ 2,000 feet) (_Annandale_); MADRAS PRESIDENCY, neighbourhood of Madras town (_J. R. Henderson_); Museum compound, Egmore (Madras town) (_Annandale_); near Bangalore (alt. _ca._ 3,000 ft.), Mysore State (Annandale); Ernakulam, Cochin (_G. Mathai_): BURMA, Kawkareik, interior of Amherst district, Tenasserim, and the Moulmein waterworks in the same district (_Annandale_).[AB] [Footnote AB: Mr. C. A. Paiva, Assistant in the Indian Museum, has lately (March 31st, 1911) obtained specimens of _S. crateriformis_ in a small pond of fresh water on Ross Island in the Andaman group. The existence of this widely distributed species on an oceanic island is noteworthy.] BIOLOGY.--_S. crateriformis_ flourishes in Calcutta throughout the year. Here it is usually found adhering to the roots of water-plants, especially _Pistia_ and _Limnanthemum_. In the case of the former it occurs at the surface, in that of the latter at the bottom. When growing near the surface or even if attached to a stone at the bottom in clear water, it is invariably of a pale yellowish or greyish colour. When growing on the roots of _Limnanthemum_ in the mud of the Gangetic alluvium, however, it is almost black, and when growing in the reddish muddy waters of the tanks round Bangalore of a reddish-brown colour. This appears to be due entirely to the absorption of minute particles of inorganic matter by the cells of the parenchyma. If black sponges of the species are kept alive in clean water, they turn pure white in less than a week, apparently because these particles are eliminated. When growing on stones the sponge, as found in India, often conforms exactly with Potts's description: "a filmy grey sponge, branching off here and there ... yet with a curious lack of continuity...." The wide efferent canals of this sponge afford a convenient shelter to small crustacea, and the isopod _Tachæa spongillicola_, Stebbing (see p. 94), is found in them more abundantly than in those of any other sponge. This is especially the case when the sponge is growing at the bottom. On the surface of the sponge I have found a peculiar protozoon which resembles the European _Trichodina spongillæ_ in general structure but belongs, I think, to a distinct species, if not to a distinct genus. Subgenus B. EUNAPIUS, _J. E. Gray_. _Eunapius_, J. E. Gray (_partim_), P. Zool. Soc. London, 1867, p. 552. _Spongilla_ (_s. str._), Vejdovsky, in Potts's "Fresh-Water Sponges," P. Ac. Philad. 1887, p. 172.