Contemporary with Carter were two authors whose monographs on the freshwater sponges did much to advance the study of the group, namely, J. S. Bowerbank, whose account of the species known at the time was published in the 'Proceedings of the Zoological Society of London' in 1882, and the veteran American naturalist Mr. Edward Potts, whose study of the freshwater sponges culminated in his monograph published in the 'Proceedings of the Academy of Natural Sciences of Philadelphia' in 1887. Carter's own revision of the group was published in the 'Annals and Magazine of Natural History' in 1881. The names of Vejdovsky, who prefaced Potts's monograph with an account of the European species, and of Dybowsky, who published several important papers on classification, should also be mentioned, while Weltner's catalogue of the known species (1895) is of the greatest possible value to students of the group. Many authors have dealt with the physiology, reproduction and development of the Spongillidæ, especially in recent years; Dr. R. Evans's description of the larva of _Spongilla lacustris_ (1899), and his account of the development of the gemmule in _Ephydatia blembingia_ (1901), Zykoff's account of the development of the gemmule and of the sponge from the gemmule (1892), and Weltner's observations on colour and other points (1893, 1907), may be mentioned in particular. Laurent's observations on development (1844), which were published in the 'Voyage de la Bonite,' and especially the exquisite plates which accompany them, have not received the notice they deserve, probably on account of their method of publication. LITERATURE. The fullest account of the literature on the Spongillidæ as yet published will be found in the first of Weltner's 'Spongillidenstudien' (Archiv für Naturgeschichte, lix (i), p. 209, 1893). Unfortunately it contains no references of later date than 1892. The following list is not a complete bibliography, but merely a list of books and papers that should prove of use to students of the Oriental Spongillidæ. (a) _Works of Reference._ 1863. BOWERBANK, "A Monograph of the Spongillidæ," P. Zool. Soc. London, 1863, pp. 440-472, pl. xxxviii. 1867. GRAY, J. E., "Notes on the arrangement of Sponges, with the description of some new genera." _ibid._ 1867, pp. 492-558. 1881. CARTER, "History and classification of the known species of _Spongilla_," Ann. Nat. Hist. (5) vii, pp. 77-107, pls. v, vi. 1883. VEJDOVSKY, "Die Süsswasserschwämme Böhmens," Abh. Kön. Böhm. Ges. Wiss. (math.-natur. Classe), xii, pp. 1-43, pls. i-iii. 1887. VOSMAER, "Spongien (Porifera)," in Bronn's Thier-Reichs. 1887. POTTS, "Contributions towards a synopsis of the American forms of Fresh-Water Sponges, with descriptions of those named by other authors and from all parts of the world," P. Ac. Philad. pp. 158-279, pls. v-xii. 1887. VEJDOVSKY, "Diagnosis of the European Spongillidæ," _ibid._ pp. 172-180.