_Spongilla_, Lamarck, Histoire des Animaux sans Vertèbres, ii, p. 111 (1836). _Spongilla_, Carter, Ann. Nat. Hist. (5) vii, p. 86 (1881). _Euspongilla_, Vejdovsky, Abh. Böhm. Ges. xii, p. 15 (1883). _Spongilla_, Potts, P. Ac. Philad. 1887, p. 182. TYPE, _Spongilla lacustris_, auctorum. Spongillidæ in which the gemmules have (normally) cylindrical or subcylindrical spicules that are sharp or blunt at the ends, without a distinct transverse disk or disks and without comb-like vertical rows of spines. The skeleton is variable in structure, sometimes being almost amorphous, sometimes having well-defined radiating and transverse fibres firmly compacted with spongin. The skeleton-spicules are either sharp or blunt at the ends. Flesh-spicules are often absent; when present they are needle-like and resemble the gemmule-spicules in general structure; they have not even rudimentary rotules at their ends. The gemmules either lie free in the substance of the sponge or are attached to its support; sometimes they adhere together in free or attached groups. _Spongilla_ is undoubtedly the most primitive genus of the Spongillidæ, its spicules showing less sign of specialization than those of any other genus included in the family. As a fossil it goes back at any rate to the Upper Jurassic (p. 52). GEOGRAPHICAL DISTRIBUTION.--Cosmopolitan. In most countries the majority of the freshwater sponges belong to this genus, but in Japan _Ephydatia_ seems to predominate. _Key to the Indian Species of_ Spongilla.