[AX] Journ. Coll. Sci. Tokyo, iv, p. 124 (1891).
[AY] Bibliotheca Zoologica, ii, pt. 6, p. 17 (1890).
[AZ] There is some doubt as to the proper name of this species, which may not be the one originally described as Membranipora lacroixii by Andouin. I follow Busk and Hincks in my identification (see Cat. Polyzoa Brit. Mus. ii, p. 60, and Hist. Brit. Polyzoa, p. 129). Levinsen calls it M. hippopus, sp. nov. (see Morphological and Systematic Studies on the Cheilostomatous Bryozoa, p. 144; Copenhagen, 1909).
[BA] Miss Thornely (Rec. Ind. Mus. i, p. 186, 1907) records it from Mergui, but this is an error due to an almost illegible label. The specimens she examined were the types of the species from Port Canning. Since this was written I have obtained specimens from Bombay—April, 1911.
[BB] Annandale, Rec. Ind. Mus. ii, p. 14 (1908).
History of the Study of the Freshwater Polyzoa.
The naturalists of the eighteenth century were acquainted with more than one species of freshwater polyzoon, but they did not distinguish these species from the hydroids. Trembley discovered Cristatella, which he called "Polype à Panache," in 1741, and Linné described a species of Plumatella under the name Tubipora repens in 1758, while ten years later Pallas gave a much fuller description (under the name Tubularia fungosa) of the form now known as Plumatella fungosa or P. repens var. fungosa. Although Trembley, Baker, and other early writers on the fauna of fresh water published valuable biological notes, the first really important work of a comprehensive nature was that of Dumortier and van Beneden, published in 1848. All previous memoirs were, however, superseded by Allman's Monograph of the Fresh-Water Polyzoa, which was issued in 1857, and this memoir remains in certain respects the most satisfactory that has yet been produced. In 1885 Jullien published a revision of the phylactolæmata and freshwater ctenostomes which is unfortunately vitiated by some curious lapses in observation, but it is to Jullien that the recognition of the proper position of Hislopia is due. The next comprehensive monograph was that of Kraepelin, which appeared in two parts (1887 and 1892) in the Abhandlungen des Naturwiss. Vereins of Hamburg. In its detailed information and carefully executed histological plates this work is superior to any that preceded it or has since appeared, but the system of classification adopted is perhaps less liable to criticism than that followed by Braem in his "Untersuchungen," published in the Bibliotheca Zoologica in 1888.
During the second half of the nineteenth century and the first decade of the twentieth several authors wrote important works on the embryology and anatomy of the phylactolæmata, notably Kraepelin, Braem, and Oka; but as yet the ctenostomes of fresh water have received comparatively little attention from anything but a systematic point of view.
From all points of view both the phylactolæmata and the ctenostomes of Asia have been generally neglected, except in the case of the Japanese phylactolæmata, which have been studied by Oka. Although Carter made some important discoveries as regards the Indian forms, he did not devote to them the same attention as he did to the sponges. In the case of the only new genus he described he introduced a serious error into the study of the two groups by placing Hislopia among the cheilostomes, instead of in its true position as the type genus of a highly specialized family of ctenostomes.