BIOLOGY.--The specimens collected by Prof. Weber in Natal and those collected by myself in the Bombay Presidency were both obtained in the month of November. It is therefore very interesting to compare them from a biological point of view. In so doing, it must be remembered that while in S. Africa November is near the beginning of summer, in India it is at the beginning of the "cold weather," that is to say, both the coolest and the driest season of the year. The lake in which my specimens were obtained had, at the time when they were collected, already sunk some inches below its highest level, leaving bare a gently sloping bank of small stones. Adhering to the lower surface of these stones I found many small patches of _Spongilla bombayensis_, quite dry but complete so far as their harder parts were concerned and with the gemmules fully formed at their base. From the shallow water at the edge of the lake I took many similar stones which still remained submerged. It was evident that the sponge had been just as abundant on their lower surface as on that of the stones which were now dry; but only the gemmules remained, sometimes with a few skeleton-spicules adhering to them (Pl. II, fig. 2). The bulk of the skeleton had fallen away and the parenchyma had wholly perished. In a few instances a small sponge, one or two millimetres in diameter, had already been formed among the gemmules; but these young sponges appeared to belong to some other species, possibly _Spongilla indica_, which was also common in the lake. Carter's specimen of _S. bombayensis_, which was evidently in much the same condition as those I found still submerged a month later, was taken in October in a disused quarry. It was surrounded by a mass of _S. carteri_ three inches in diameter, and was attached to a herbaceous annual. The point on the edge of the quarry at which this plant grew was not reached by the water until July. It is therefore necessary to assume that the gemmules of _S. bombayensis_ had been formed between July and October. Probably the larva of the sponge had settled down on the plant during the "rains"--which commence in Bombay about the beginning of June--and had grown rapidly. The production of gemmules may have been brought about owing to the sponge being choked by the more vigorous growth of _S. carteri_, a species which grows to a considerable size in a comparatively short time, while _S. bombayensis_ apparently never reaches a thickness of more than a few millimetres. The manner in which the gemmules of _S. bombayensis_ are fastened to the solid support of the sponge must be particularly useful in enabling them to sprout in a convenient environment as soon as the water reaches them. The fact that the gemmules remained fixed without support renders it unnecessary for the skeleton to persist as a cage containing them (or at any rate a proportion of them) during the period of rest.