B. Skeleton-spicules smooth. Skeleton-spicules sharp; gemmule spicules very irregular in form _ultima_, p. 104. Subgenus A. EUSPONGILLA, _Vejdovsky_. _Euspongilla_, Vejdovsky, Abh. Böhm. Ges. xii, p. 15 (1883). _Euspongilla_, _id._, in Potts's "Fresh-Water Sponges," P. Ac. Philad. 1887, p. 172. _Euspongilla_, Weltner, in Zacharias's Tier- und Pflanzenwelt des Süsswassers, i, p. 210 (1891). TYPE, _Spongilla lacustris_, auctorum. Spongillæ in which the gemmules are covered with a thick, apparently granular pneumatic coat. A delicate membrane often occurs outside this coat, but it is never thick or horny. The gemmules usually lie free in the sponge but sometimes adhere to its support; rarely they are fastened together in groups (_e. g._ in _S. aspinosa_, Potts). The skeleton-spicules are never very stout and the skeleton is always delicate. The species in this subgenus are closely allied and must be distinguished rather by the sum of their peculiarities than by any one character. They occur in all countries in which Spongillidæ are found. Seven Indian species may be recognized. 1. Spongilla lacustris, _auctorum_. _Spongilla lacustris_, Bowerbank, P. Zool. Soc. London, 1863, p. 441, pl. xxxviii, fig. 14. _Spongilla lacustris_, Carter, Ann. Nat. Hist. (5) vii, p. 87 (1881). _Euspongilla lacustris_, Vejdovsky, in Potts's "Fresh-Water Sponges," P. Ac. Philad. 1887, p. 172. _Spongilla lacustris_, Potts, _ibid._, p. 186, pl. v, fig. 1, pl. vii, figs. 1-6. _Euspongilla lacustris_, Weltner, in Zacharias's Tier- und Pflanzenwelt des Süsswassers, i, p. 211, figs. 36-38 (1891). _Spongilla lacustris_, _id._, Arch. Naturg. lxi (i), pp. 118, 133-135 (1895). _Spongilla lacustris_, Annandale, J. Linn. Soc., Zool., xxx, p. 245 (1908). [I have not attempted to give a detailed synonymy of this common species. There is no means of telling whether many of the earlier names given to forms or allies of _S. lacustris_ are actual synonyms, and it would serve no useful purpose, so far as the fauna of India is concerned, to complicate matters by referring to obscure descriptions or possible descriptions of a species only represented in India, so far as we know, by a specialized local race, to which separate references are given.]