BIOLOGY.--_L. carteri_ is found on the lower surface of stones and on the stems and leaves of water-plants, usually in lakes or large ponds. Although the zoaria do not form compound colonies by secreting a common membrane or investment, they are markedly gregarious. The most closely congregated and the largest zoaria I have seen were assembled amongst a gelatinous green alga of the genus _Tolypothrix_[BM] (Myxophyceæ) that grows on the vertical stems of a plant at the edge of Igatpuri Lake; it is noteworthy that in this case the alga seemed to take the place of the common investment of _Pectinatella burmanica_, in which green cells are present in large numbers (p. 237). The zoaria of _L. carteri_ are able to change their position, and I found that if a number of them were placed in a bottle of water they slowly came together at one spot, thus apparently forming temporary compound colonies. Before a movement of the whole zoarium commences its base becomes detached from its support at the anterior end (fig. 32, p. 172), but the whole action is extremely slow and I have not been able to discover any facts that cast light on its exact method of production. At Igatpuri statoblasts are being produced in considerable numbers at the end of November, but many young zoaria can be found in which none have as yet been formed. [Footnote BM: Prof. W. West will shortly describe this alga, which represents a new species, in the Journ. Asiat. Soc. Bengal, under the name _Tolypothrix lophopodellophila_.--_April 1911_.] The larva of a fly of the genus _Chironomus_ is often found inhabiting a tube below zoaria of _L. carteri_. It is thus protected from its enemies but can protrude its head from beneath the zoarium and seize the small animals on which it preys. Genus 4. PECTINATELLA, _Leidy_. _Cristatella_, Leidy, P. Ac. Philad. v, p. 265 (1852). _Pectinatella_, _id._, _ibid._, p. 320. _Pectinatella_, Allman, Mon. Fresh-Water Polyzoa, p. 81 (1857). _Pectinatella_, Hyatt, Proc. Essex Inst. v, p. 227, fig. 20 (1867). _Pectinatella_, Kraepelin, Deutsch. Süsswasserbryozoen, i, p. 133 (1887). _Pectinatella_, Oka, Journ. Coll. Sci. Tokyo, iv, p. 89 (1891). TYPE, _Pectinatella magnifica_, Leidy. This genus is closely allied to _Lophopodella_, from which it is often difficult to distinguish young specimens. Adult zoaria are, however, always embedded together in groups in a gelatinous investment which they are thought to secrete in common[BN], and the statoblasts are entirely surrounded by processes that bear curved spinules at their tips only. The polypides have the same semi-recumbent position as those of _Lophopodella_ but are larger than those of any species of _Lophopodella_ or _Lophopus_ yet known. The statoblasts are larger than those of any other Plumatellidæ.