The zooecia are arranged in a regular cruciform manner and arise either directly one from another or with the intervention of tubular processes. If the polypide has a gizzard it does not bear internal chitinous projections. Most of the species are confined to fresh water, but a few are found in brackish water or even in the sea.
Although all true freshwater Ctenostomes belong to the fourth of these divisions, species of a genus (_Bowerbankia_) included in the third are so frequently found in brackish water and in association with one belonging to the fourth, and are so easily confounded with the latter, that I think it necessary to include a brief description of the said genus and of the form that represents it in ponds of brackish water in India.
SYSTEMATIC LIST OF THE INDIAN FRESHWATER POLYZOA.
[The types have been examined in the case of all species, etc., whose names are marked thus, *.]
[_B. caudata_ subsp. _bengalensis_*, Annandale (1907). (Brackish water).]
27. _H. lacustris_, Carter (1858). 27 _a._ _H. lacustris_ subsp. _moniliformis_*, nov.
29. _P. fruticosa_, Allman (1844). 30. _P. emarginata_, Allman (1844). 31. _P. javanica_*, Kraepelin (1905). 32. _P. diffusa_, Leidy (1851). 33. _P. allmani_, Hancock (1850). 34. _P. tanganyikæ_*, Rousselet (1907). 35. _P. punctata_, Hancock (1850).
37. _L. carteri_* (Hyatt) (1865). 37 _a._ _L. carteri_ var. _himalayana_* (Annandale) (1907).
VESICULARIDÆ, Hincks, Brit. Marine Polyzoa, p. 512 (1880).
Zooecia constricted at the base, deciduous, attached to a stem that is either recumbent or vertical.
_Bowerbankia_, Farre, Phil. Trans. Roy. Soc. cxxvii, p. 391 (1837).
_Bowerbankia_, Hincks, _op. cit._ p. 518.
_Zoarium_ vertical or recumbent. _Zooecia_ ovate or almost cylindrical, arranged on the stem singly, in clusters or in a subspiral line. _Polypide_ with 8 or 10 tentacles.
_Bowerbankia caudata_, Hincks, _op. cit._ p. 521, pl. lxxv, figs. 7, 8.
This species is easily distinguished from all others by the fact that mature zooecia have always the appearance of being fixed to the sides of a creeping, adherent stem and are produced, below the point at which they are thus fixed, into a pointed "tail."
_Bowerbankia caudata_, Thornely, Rec. Ind. Mus. i, p. 196 (1907).