(4) the gemmule-spicules are longer and more slender and are never strongly bent.
As regards the form of the skeleton- and gemmule-spicules and also that of the branches the subspecies reticulata resembles S. alba rather than S. lacustris, but owing to the fact that it agrees with S. lacustris in its profuse production of branches, in possessing green corpuscles and in its fragility, I think it should be associated with that species.
Fig. 8.
A=gemmule-spicules of Spongilla lacustris subsp. reticulata (from type); B=gemmule-spicules of S. alba from Calcutta: both highly magnified.
The branches are sometimes broad (fig. 5, p. 37), sometimes very slender. In the latter condition they resemble blades of grass growing in the water.
Type in the Indian Museum; a co-type in the British Museum.
Geographical Distribution.—All over Eastern India and Burma; also in the Bombay Presidency. Localities:—Bengal, Port Canning, Ganges delta; Rajshahi (Rampur Bhulia) on the Ganges, 150 miles N. of Calcutta (Annandale); Puri district, Orissa (Annandale); R. Jharai, Siripur, Saran district, Tirhut (M. Mackenzie): Madras Presidency, Madras (town) (J. R. Henderson): Bombay Presidency, Igatpuri, W. Ghats (Annandale).
Biology.—This subspecies is usually found in small masses of water, especially in pools of rain-water, but Mr. Mackenzie found it growing luxuriantly in the Jharai at a time of flood in September. It is very abundant in small pools among the sand-dunes that skirt the greater part of the east coast of India. Here it grows with great rapidity during the "rains," and often becomes desiccated even more rapidly as soon as the rain ceases. As early in the autumn as October I have seen masses of the sponge attached, perfectly dry, to grass growing in the sand near the Sur Lake in Orissa. They were, of course, dead but preserved a life-like appearance. Some of them measured about six inches in diameter. At Port Canning the sponge grows during the rains on the brickwork of bridges over ditches of brackish water that dry up at the beginning of winter, while at Rajshahi and at Igatpuri I found it at the edges of small ponds, at the latter place in November, at the former in February. Specimens taken at Madras by Dr. Henderson during the rains in small ponds in the sand contained no gemmules, but these structures are very numerous in sponges examined in autumn or winter.
Numerous larvæ of Sisyra indica (p. 92) were found in this sponge at Rajshahi. Unlike those obtained from S. alba, they had a green colour owing to the green matter sucked from the sponge in their stomachs. The coralloides phase of Plumatella fruticosa (p. 219) was also found in S. lacustris subsp. reticulata at Rajshahi.