_Spongilla crassissima_, _id._, Rec. Ind. Mus. i. p. 390, pl. xiv, fig. 4 (1907). _Sponge_ very hard and strong, nearly black in colour, sometimes with a greenish tinge, forming spherical, spindle-shaped or irregular masses without branches but often several inches in diameter. Oscula circular or star-shaped, usually surrounded by radiating furrows; pores normally contained in single cells. External membrane closely adherent to the sponge except immediately round the oscula. _Skeleton_ dense, compact and only to be broken by the exercise of considerable force; radiating and transverse fibres not very stout but firmly bound together by spongin (fig. 6, p. 38), which occasionally extends between them as a delicate film; their network close and almost regular. _Spicules._ Skeleton-spicules smooth, feebly curved, sausage-shaped but by no means short, as a rule bearing at each end a minute conical projection which contains the extremity of the axial filament. No flesh-spicules. Gemmule-spicules closely resembling those of _S. fragilis_ subsp. _calcuttana_, but as a rule even more obtuse at the ends. _Gemmules_ as in _S. fragilis_ subsp. _calcuttana_; a basal layer of gemmules rarely formed. 11 _a._ Var. crassior*, _Annandale_. _Spongilla crassior_, Annandale, Rec. Ind. Mus. i, p. 389, pl. xiv, fig. 3 (1907). This variety differs from the typical form chiefly in its even stronger skeleton (fig. 3, p. 33) and its stouter skeleton-spicules, which do not so often possess a terminal projection. The sponge is of a brownish colour and forms flat masses of little thickness but of considerable area on sticks and on the stems of water-plants. TYPES.--The types of both forms are in the Indian Museum. Co-types have been sent to London. GEOGRAPHICAL DISTRIBUTION.--This sponge is only known from Bengal. The variety _crassior_ was found at Rajshahi (Rampur Bhulia) on the Ganges, about 150 miles N. of Calcutta, while the typical form is fairly common in the "tanks" of Calcutta and very abundant in the Sur Lake near Puri in Orissa. [Illustration: Fig. 16.--Spicules of _Spongilla crassissima_ var. _crassior_ (from type specimen), × 240.]