Various small oligochæte worms (e. g., _Chætogaster spongillæ_,[BG] _Nais obtusa_, _Nais elinguis_, _Slavina appendiculata_ and _Pristina longiseta_[BH]), take shelter amongst them; dipterous larvæ of the genus _Chironomus_ often build their protective tubes at the base of the zoaria, and the surface of the zooecia commonly bears a more or less profuse growth of such protozoa as _Vorticella_ and _Epistylis_. I have seen a worm of the genus _Chætogaster_ devouring the tentacles of a polypide that had been accidentally injured, but as a rule the movements of the lophophore are too quick to permit attacks of the kind, and I know of no active enemy of the genus. The growth of sponges at the base of the zoaria probably chokes some species, but one form (_F. fruticosa_) is able to surmount this difficulty by elongating its zooecia (p. 219). A small worm (_Aulophorus tonkinensis_) which is common in ponds in Burma and the east of India as far west as Lucknow, often builds the tube in which it lives mainly of the free statoblasts of this genus. It apparently makes no selection in so doing but merely gathers the commonest and lightest objects it can find, for small seeds and minute fragments of wood as well as sponge gemmules and statoblasts of other genera are also collected by it. I know of no better way of obtaining a general idea as to what sponges and phylactolæmata are present in a pond than to examine the tubes of _Aulophorus tonkinensis_. [Footnote BG: Annandale, J. As. Soc. Bengal (n. s.) ii, p. 188, pl. i (1906).] [Footnote BH: See Michaelsen, Mem. Ind. Mus. i, pp. 131-135 (1908).]