GEOGRAPHICAL DISTRIBUTION.--_S. lacustris_ occurs all over Europe and N. America and is probably the commonest species in most parts of both continents. It has also been found in Northern Asia and may occur in the Himalayan lakes and in the north-west of India. 1 _a._ Subspecies reticulata*, _Annandale_. _Spongilla reticulata_, Annandale, Rec. Ind. Mus. i, p. 387, pl. xiv, fig. 1 (1907). _Spongilla lacustris_ subspecies _reticulata_, _id._, P. U.S. Mus. xxxvii, p. 401 (1909). This race differs from the typical _S. lacustris_ in the following particulars:-- (1) The branches are always compressed and anastomose freely when well developed (fig. 5, p. 37); (2) the skeleton-fibres are finer; (3) the skeleton-spicules are longer; (4) the gemmule-spicules are longer and more slender and are never strongly bent. [Illustration: Fig. 8. A=gemmule-spicules of _Spongilla lacustris_ subsp. _reticulata_ (from type); B=gemmule-spicules of _S. alba_ from Calcutta: both highly magnified.] As regards the form of the skeleton- and gemmule-spicules and also that of the branches the subspecies _reticulata_ resembles _S. alba_ rather than _S. lacustris_, but owing to the fact that it agrees with _S. lacustris_ in its profuse production of branches, in possessing green corpuscles and in its fragility, I think it should be associated with that species. The branches are sometimes broad (fig. 5, p. 37), sometimes very slender. In the latter condition they resemble blades of grass growing in the water. TYPE in the Indian Museum; a co-type in the British Museum. GEOGRAPHICAL DISTRIBUTION.--All over Eastern India and Burma; also in the Bombay Presidency. _Localities:_--BENGAL, Port Canning, Ganges delta; Rajshahi (Rampur Bhulia) on the Ganges, 150 miles N. of Calcutta (_Annandale_); Puri district, Orissa (_Annandale_); R. Jharai, Siripur, Saran district, Tirhut (_M. Mackenzie_): MADRAS PRESIDENCY, Madras (town) (_J. R. Henderson_): BOMBAY PRESIDENCY, Igatpuri, W. Ghats (_Annandale_).