In the cheilostomes certain individuals of each zoarium are often profoundly modified in shape and function and exhibit almost constant rhythmical or convulsive movements, some ("avicularia") being shaped like a bird's beak and snapping together, others ("vibracula") being more or less thread-like and having a waving motion. DISTRIBUTION OF THE FRESHWATER POLYZOA. Fifteen genera of freshwater Polyzoa are now recognized, one entoproctous and fourteen ectoproctous; five of the latter are ctenostomatous and nine phylactolæmatous. Of the fourteen ectoproctous genera seven are known to occur in India, viz., _Victorella_, _Hislopia_, _Fredericella_, _Plumatella_, _Stolella_, _Lophopodella_, and _Pectinatella_. Except _Stolella_, which is only known from northern India, these genera have an extremely wide geographical range; _Victorella_ occurs in Europe, India, Africa, and Australia; _Hislopia_ in India, Indo-China, China, and Siberia; _Fredericella_ in Europe, N. America, Africa, India, and Australia; _Plumatella_ in all geographical regions; _Lophopodella_ in E. and S. Africa, India, and Japan; _Pectinatella_ in Europe, N. America, Japan, and India. Two genera, _Paludicella_ and _Lophopus_, have been stated on insufficient grounds to occur in India. The former is known from Europe and N. America, and is said to have been found in Australia, while the latter is common in Europe and N. America and also occurs in Brazil. Of the genera that have not been found in this country the most remarkable are _Urnatella_ and _Cristatella_. The former is the only representative in fresh water of the Entoprocta and has only been found in N. America. Each individual is borne upon a segmented stalk the segments of which are enclosed in strong horny coverings and are believed to act as resting buds. _Cristatella_, which is common in Europe and N. America, is a phylactolæmatous genus of highly specialized structure. It possesses a creeping "sole" or organ of progression at the base of the zoarium. The other phylactolæmatous genera that do not occur in India appear to be of limited distribution, for _Australella_ is only known from N. S. Wales, and _Stephanella_ from Japan. The ctenostomatous _Arachnoidea_ has only been reported from Lake Tanganyika, and _Pottsiella_ only from a single locality in N. America. As regards the exotic distribution of the Indian species little need be said. The majority of the _Plumatellæ_ are identical with European species, while the only species of _Fredericella_ that has been discovered is closely allied to the European one. The Indian species of _Lophopodella_ occurs also in E. Africa and Japan, while that of _Pectinatella_ is apparently confined to India, Burma and Ceylon, but is closely allied to a Japanese form. POLYZOA OF BRACKISH WATER.