II. Some or all of the microscleres birotulate. (Birotulate microscleres of one kind only.) A. Microscleres of the gemmule birotulate, the rotules with serrated or strongly sinuous edges; parenchyma spicules usually absent, never of complicated structure EPHYDATIA, p. 108. B. Microscleres of the gemmule as in _Ephydatia_; microscleres of the parenchyma consisting of numerous shafts meeting in different planes in a central nodule DOSILIA, p. 110. C. Microscleres as in _Ephydatia_ except that the rotulæ of the gemmule-spicules have smooth edges TROCHOSPONGILLA, p. 113. D. Microscleres of the gemmule without a trace of rotules, those of the parenchyma birotulate CORVOSPONGILLA, nov., p. 122. III. Microscleres of the gemmule with a well-developed basal rotule and a vertical shaft ending above in a mere knob. TUBELLA, p. 120. The most distinct genus of Spongillidæ not yet found in India is _Heteromeyenia_, Potts. It is easily distinguished from all others by the fact that the birotulate spicules of the gemmule are of two quite distinct kinds, which occur together on every mature gemmule. _Heteromeyenia_ is represented by several American species, one of which has been found in Europe. _Acalle_, J. E. Gray, which is represented by a single South American species (_Spongilla recurvata_, Bowerbank), is related to _Heteromeyenia_ but has one kind of gemmule-spicule tubelliform, the other birotulate. Probably _Uraguaya_, Carter, should be regarded as a subgenus of _Trochospongilla_ with an unusually solid skeleton; it is peculiar to S. America. _Parmula_, Carter (=_Drulia_, Gray) includes South American forms allied to _Tubella_, but with the shaft of the gemmule-spicule degenerate and consisting of a mere projection in the centre of a shield-like body, which represents the lower rotule. The status of _Potamolepis_, Marshall, originally described from the Lake of Galilee, is very doubtful; possibly some or all of its species belong to the subgenus of _Spongilla_ here called _Stratospongilla_ (p. 100); but they are stated never to produce gemmules. The same is the case as regards _Pachydictyum_, Weltner, which consists of a single species from Celebes. The sponges from Lake Baikal assigned by Weltner (Arch. Naturg. lxi (i) p. 131) to the subfamily Lubomirskinæ are of doubtful position and need not be considered here; while _Lessepsia_, Keller, from one of the salt lakes on the Suez Canal, certainly does not belong to the family, although it is assigned to it by von Lendenfeld (Mon. Horny Sponges, p. 904 (1889)) and subsequently by Minchin (Porifera, p. 152, in Lankester's Treatise on Zoology, part ii (1900)). Genus 1. SPONGILLA, _Lamarck_ (Carter _emend._).