So far as my experience goes, this subspecies has always a bright green colour due to the presence of "green corpuscles," even when it is growing in a pond heavily shaded by trees or under the arch of a small bridge. Probably the more intense light of India enables the corpuscles to flourish in situations in which in Europe they would lose their chlorophyll.
2. Spongilla proliferens*, Annandale.
Spongilla cinerea, Weber (nec Carter), Zool. Ergeb. Niederl. Ost-Ind. vol. i, pp. 35, 46 (1890). Spongilla proliferens, Annandale, J. Asiat. Soc. Bengal, 1907, p. 15, fig. 1. Spongilla proliferens, id., Rec. Ind. Mus. i, pp. 267, 271 (1907).
Sponge forming soft, shallow cushions rarely more than 10 cm. in diameter on the leaves of water-plants, or small irregular masses on their roots and stems. Colour bright green. Oscula moderate, flat, surrounded by deep, cone-shaped collars; radiating furrows and canals in the parenchyma surrounding them often deep. External pores contained normally in single cells. The surface frequently covered by small rounded buds; true branches if present more or less flattened or conical, always short, as a rule absent.
Skeleton loose, feebly reticulate at the base of the sponge; transverse fibres slender in the upper part of the sponge, often scarcely recognizable at its base. Very little spongin present.
Spicules. Skeleton-spicules long, smooth, sharply pointed; the length on an average at least 20 times the greatest breadth, often more. Flesh-spicules slender, gradually pointed, nearly straight, covered with minute straight or nearly straight spines. Gemmule-spicules very similar, but usually a little stouter and often blunt at the ends; their spines rather longer than those on the flesh-spicules, usually more numerous near the ends than in the middle of the spicule, slightly retroverted, those at the extreme tips often so arranged as to suggest a rudimentary rotule.
Fig. 9.—Gemmule of Spongilla proliferens as seen in optical section (from Calcutta), × 140.
Gemmules usually numerous, lying free near the base of the sponge, very variable in size, spherical, surrounded by a thick granular layer in which the spicules, which are always very numerous, are arranged tangentially, their position being more near the vertical than the horizontal; a few horizontal spicules usually present on the external surface of the gemmule, which frequently has a ragged appearance owing to some of the tangential spicules protruding further than others. Foraminal tubule stout, cylindrical, usually somewhat contorted; its orifice irregular in outline. Sometimes more than one foramen present.
S. proliferens can be distinguished from all forms of S. lacustris and S. alba by the fact that its gemmules possess a foraminal tubule; from S. cinerea it can be distinguished by its colour and its smooth skeleton-spicules, and from S. travancorica by its free gemmules. I have been enabled by the kindness of Prof. Max Weber to examine specimens from Celebes and Java identified by him as S. cinerea, Carter, and have no doubt that they belong to my species.