_Plumatella_, Lamarck, Animaux sans Vert. (ed. 1re) ii, p. 106 (1816). _Alcyonella_, _id_., _ibid_. p. 100. _Plumatella_, Allman, Mon. Fresh-Water Polyzoa, p. 92 (1857). _Alcyonella_, _id_., _ibid_. p. 86. _Plumatella_, Hyatt, Comm. Essex Inst. iv, p. 207, pl. viii (1866). _Plumatella_, Jullien (_partim_), Bull. Soc. zool. France, x, p. 100 (1885). _Hyalinella_, _id_., _ibid_. p. 133. _Plumatella_, Kraepelin, Deutsch. Süsswass. Bryozoen, i, p. 104 (1887). _Plumatella_, Braem, Unter. ü. Bryozoen des süssen Wassers, p. 2 (Bibliotheca Zoologica, ii, 1890). _Zoarium_ dendritic, recumbent, erect, or partly recumbent and partly erect. _Zooecia_ tubular, not confined in a gelatinous synoecium; the ectocyst usually horny. _Statoblasts_ often of two kinds, free and stationary, the latter without air-cells and as a rule adherent by one surface, the former provided with a well-developed ring of air-cells but without marginal processes, oval in form, never more than about 0.6 mm. in length. _Polypide_ with less than 65 tentacles. [Illustration: Fig. 42.--Outlines of free statoblasts of _Plumatella_ (enlarged). A, of _P. fruticosa_ (Calcutta); B, of _P. emarginata_ (Calcutta); C, of _P. javanica_ (Travancore); D, of _P. diffusa_ (Sikhim); E, of _P. allmani_ (Bhim Tal); F, of _P. diffusa_ (Rajshahi, Bengal); G, G', of _P. punctata_ (Calcutta); H, of _P. diffusa_ (Sikhim), statoblast further enlarged: A=outline of capsule; B=limit of swim-ring on ventral surface; C=limit of swim-ring on dorsal surface. [The dark area represents the capsule of the statoblast.]]