_Loxosomatoides_[BB] (fig. 34), the Indian entoproctous genus found in brackish water, has not as yet been obtained from the open sea, but has recently been introduced, apparently from a tidal creek, into isolated ponds of brackish water at Port Canning. It is easily recognized by the chitinous shield attached to the ventral (posterior) surface. [Footnote BB: Annandale, Rec. Ind. Mus. ii, p. 14 (1908).] [Illustration: Fig. 34.--_Loxosomatoides colonialis_, Annandale. A and B, a single individual of form A, as seen (A) in lateral, and (B) in ventral view; C, outline of a similar individual with the tentacles retracted, as seen from in front (dorsal view); D, ventral view of an individual and bud of form B. All the figures are from the type specimens and are multiplied by about 70.] II. 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 All previous memoirs were, however, superseded by Allman's Monograph of the Fresh-Water Polyzoa, which was issued in 1857, and this memoir remains in certain respects the most satisfactory that has yet been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.