Polypides are as a rule found in an active condition only in the cold weather, but I have on one occasion seen them in this condition in August, in a small zoarium attached to a shell of Melania tuberculata taken in a canal of brackish water near Calcutta.
Family HISLOPIIDÆ.
Hislopidées, Jullien, Bull. Soc. zool. France, x, p. 180 (1885). Hislopiidæ, Annandale, Rec. Ind. Mus. i, p. 200 (1907).
Zoarium recumbent, often forming an almost uniform layer on solid subjects.
Zoœcia flattened, adherent; the orifice dorsal, either surrounded by a chitinous rim or situated at the tip of an erect chitinous tubule; no parietal muscles.
Polypide with an ample gizzard which possesses a uniform chitinous lining and does not close together when the polypide is retracted.
Resting bud, not produced.
Only two genera can be recognized in this family, Arachnoidea, Moore, from Central Africa, and Hislopia, Carter, which is widely distributed in Eastern Asia. The former genus possesses an upright orificial tubule and has zoœcia separated by basal tubules. Its anatomy is imperfectly known, but it certainly possesses a gizzard of similar structure to that of Hislopia, between which and Victorella its zoœcium is intermediate in form.
Genus HISLOPIA, Carter.