Neither the mouth nor cirri present any deviations from the generic character.
3. [CHELONOBIA] PATULA. Pl. [14], fig. [3 a], [3 b], [4].
CORONULA PATULA. Ranzani. Memoire di Storia Naturale (1820), Tab. 3, fig. 25-28.
ASTROLEPAS LÆVIS. J. E. Gray (!). Annals of Philosophy (new series), vol. 10, 1825.
VERRUCA CANCRI AMERICANI. Ellis. Phil. Trans., vol. 50, 1758, Pl. 34, fig. 13.
Shell steeply conical, very smooth and light; orifice large, generally exceeding half the basal diameter of the shell: radii broad, smooth, only slightly depressed.
Hab.—Mediterranean; Gambia, West Africa; Charlestown; Jamaica; Honduras; Brazil; Australia. Attached to Crustacea, smooth univalve shells, and apparently to ships’ bottoms.
General Appearance.—Shell white, very smooth, of little specific gravity, steeply conical, but not high; orifice broadly oval, polygonal, very large, namely, generally exceeding half the basal diameter of the shell. The summits of the compartments are usually perfectly preserved, pointed, and often a little recurved. The radii are rather broad, very smooth, with their summits slightly oblique and arched: they are seated only a little below the general level of the parietes. I have seen one specimen rather more than one and a half inch in basal diameter, but this is an unusual size; this species not growing to so large a size as the two foregoing forms.