CHAMACEA. Lam. A family belonging to the order Conchifera Dimyaria, Lam. described as inequivalve, attached, irregular; with or without a single rough tooth on the hinge; with two lateral muscular impressions in each valve. This family contains the genera-- 1. CHAMA. Leafy; umbones spiral. Fig. 153. 2. ETHERIA. Very irregular, pearly, without teeth. Fig. 155. 3. DICERAS. Like Chama, but the umbones free, produced. Fig. 154. CHAMBERED. When the cavity of a shell is not continuous, but is divided by shelly diaphragms or septa, it is said to be chambered. This is the case with the shells of the Polythalamous Cephalopoda, as in the Nautilus (see Introduction). The character is not confined to these, as it occurs in some species of Spondyli, and in several turrited univalves. CHAMOSTRÆA. De Roissy. CLEIDOTHÆRUS. Stutch. CHARYBS. Montf. A genus of microscopic Foraminifera. CHELIBS. Montf. A genus of microscopic Foraminifera. CHELINOTUS. Sw. A genus of "HALIOTIDÆ," Sw. including Velutina, Lam. a species of Sigaretus from Tonga, and Coriocella, Bl. Thus described, "Animal cheloniform, broad; depressed; the mantle larger than the shell, lobed in front; tentacula two, short, obtuse; eyes basal; mouth circular; shell ear-shaped, thin, fragile, imperforate; pillar none." CHELONOBIA. Leach. CORONULA Testudinaria, Auct. Fig. 15. CHERSINA. Humph. ACHATINA, Lam. CHICOREUS. Montf. A generic division of the genus MUREX, consisting of such species as have three ramified varices. _Ex._ M. inflatus, fig. 395. CHILINA. Gray. _Fam._ Auriculacea, Bl. Colimacea, Lam.--_Descr._ Oval, thin, covered with an olive green epidermis; spire rather short, consisting of few whorls; aperture large, oval, rounded anteriorly; outer lip thin, joining the inner lip without a sinus; inner lip spread over part of the body whorl, terminating in a thick columella with one or two folds.--_Obs._ These shells differ from the true Auriculæ in the thinness of the outer lip. C. Dombeyana (Auricula Dombeyana, Auct.) Fig. 300. The illustrated catalogue published by the author (Sow. Conch. illustr. parts 135, 136) contains 13 species. Rivers of South America. CHILOTREMA. Leach. A sub-genus of HELIX, containing Helix lapicida, Auct. Gray, Turton, p. 140. CHIMOTREMA. ----? Belongs to HELIX. CHIONE. Megerle. CYTHERÆA maculosa, (fig. 117, c.) sulcata, circinata, &c. Auct. and other similar species. CHIRONA. Gray. A genus of Balanidæ, the shells consisting of six parietal valves and two opercular valves; the upper edges of the parietal valves are sloped and the structure is not tubular.