_Sponge_ massive, as a rule with the surface smooth and rounded, occasionally bearing irregular ridges, which may even take the form of cockscombs; the oscula large, rounded, conspicuous but not raised above the surface of the sponge, leading into broad vertical canals; the lateral canals, except in the immediate vicinity of the central vertical ones, not very broad; the oscular collars extending for a considerable distance over the oscula in living or well-preserved specimens, never standing out from the surface; the oscula never surrounded by radiating furrows. The inhalent pores surrounded externally by unmodified cells of the external membrane. Colour greyish, sometimes with a flush of green on the external surface. The sponge has a peculiarly strong and offensive smell. _Skeleton_ fairly compact, with well-developed radiating fibres; the transverse fibres splayed out at either end so that they sometimes resemble a pair of fans joined together by the handles (fig. 3, p. 33). A moderate amount of spongin present. _Spicules._ Skeleton-spicules smooth, pointed, nearly straight, never very stout but somewhat variable in exact proportions. Gemmule-spicules similar but much smaller. (There are no true flesh-spicules, but immature skeleton-spicules may easily be mistaken for them.) _Gemmules_ as a rule numerous, spherical or flattened at the base, variable in size, each covered by a thick coat consisting of several layers of relatively large polygonal air-spaces. A single aperture surrounded by a crater-like depression in the cellular coat and provided with a foraminal tubule resembling an inverted bottle in shape. (This tubule, which does not extend beyond the surface of the cellular coat, is liable to be broken off in dried specimens.) The spicules variable in quantity, arranged irregularly among the spaces of the cellular coat and usually forming a sparse horizontal layer on its external surface. Each gemmule contained in a cage of skeleton-spicules, by the pressure of which it is frequently distorted. 8_a._ Var. mollis*, nov. This variety is characterized by a paucity of skeleton-spicules. The sponge is therefore soft and so fragile that it usually breaks in pieces if lifted from the water by means of its support. Owing to the paucity of skeleton-spicules, which resemble those of the typical form individually, the radiating and transverse fibres are extremely delicate. Common in Calcutta. 8_b._ Var. cava*, nov. This variety is characterized by the fact that the oscula open into broad horizontal canals, the roof of which is formed by a thin layer of parenchyma and skeleton or, in places, of the external membrane only. The skeleton is loose and fragile, and the living sponge has a peculiar glassy appearance. In spirit the colour is yellowish, during life it is greenish or white. Taken at Bombay; November, 1907. 8_c._ Var. lobosa*, nov.