In Weltner's catalogue of the freshwater sponges (1895) seventy-six recent species of Spongillidæ (excluding _Lubosmirskia_) are enumerated, and the number now known is well over a hundred. In India we have twenty-nine species, subspecies, and varieties, while from the whole of Europe only about a dozen are known. In the neighbourhood of Calcutta nine species, representing three genera and a subgenus, have been found; all of them occur in the Museum tank. The only other region of similar extent that can compare with India as regards the richness of its freshwater sponge fauna is that of the Amazon, from which about twenty species are known. From the whole of North America, which has probably been better explored than any other continent so far as Spongillidæ are concerned, only twenty-seven or twenty-eight species have been recorded. The Indian species fall into seven genera, one of which (_Spongilla_) consists of three subgenera. With one exception (that of _Pectispongilla_, which has only been found in Southern India) these genera have a wide distribution over the earth's surface, and this is also the case as regards the subgenera of Spongilla. Four genera (_Heteromeyenia_, _Acalle_, _Parmula_, and _Uruguaya_) that have not yet been found in India are known to exist elsewhere. Five of the Indian species are known to occur in Europe, viz., _Spongilla lacustris_, _S. crateriformis_, _S. carteri_, _S. fragilis_, _Trochospongilla pennsylvanica_; while _Ephydatia meyeni_ is intermediate between the two commonest representatives of its genus in the Holarctic Zone, _Ephydatia fluviatilis_ and _E. mülleri_. Of the species that occur both in India and in Europe, two (_Spongilla lacustris_ and _S. fragilis_) are found in this country in forms sufficiently distinct to be regarded as subspecies or local races. Perhaps this course should also be taken as regards the Indian forms of _S. carteri_, of which, however, the commonest of the Indian races would be the typical one; but _S. crateriformis_ and _T. pennsylvanica_ seem to preserve their specific characters free from modification, whether they are found in Europe, Asia, or America. The freshwater sponges of Africa have been comparatively little studied, but two Indian species have been discovered, _S. bombayensis_ in Natal and _S. alba_ var. _cerebellata_ in Egypt. Several of the species from the Malabar Zone are, moreover, closely allied to African forms (p. 11). FOSSIL SPONGILLIDÆ.