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alive, MZSP 28698 (Simone col., 27/x/1996). Remarks. Although the specimens from Caribbean present in the shell some differences with those from Brazil (figs 21-24), they have uniformity of the inner anatomical characters. A separation in specific leveł is then poorly recommended. A/. modulus differs anatomically from M. candidus Petit (cf. Risbec, 1927, figs 26, 27) in having esophagus not so broad and its insertion not near from intestine origin.

Family Cerithiidae

Gcnus Cerithium Bruguiere, 1789 (Type species: C. nodulosum Bruguiere, 1789)

Cerithium atratum (Bom, 1778)

(Figs 25,26, 67, 100, 101,314-328)

Synonymy see Marcus & Marcus (1964: 497), Houbrick (1974: 54). Complement:

Cerithium atratum: Morretes, 1949: 79; Rios, 1970: 42 (pl. 9); Abbott, 1974: 104 (fig. 992); Rios 1975:47 (pl. 13, f. 172);01iveiraetal., 1981: 101; Abbott & Dance, 1983: 66 (fig.); Leal, 1991:360.

Cerithium (Thericium) atratum: Rios, 1985:49 (pl. 19, f. 220); 1994:62 (pl. 21, f. 235)

Description.

Shell (figs 25, 26). Described by Kobelt (1898: 192), Marcus & Marcus (1964: 497-498), Houbrick (1974: 54) and others.

Head-foot (figs 314, 315, 319, 320). Color dark brown spots sparse in integument, sometimes very intense, inclusive pedał sole. Snout relatively very large, dorso-ventrally flattened, bilobed ante-rior margin. Tentacles relatively short (about half of snout length), each with a smali ommatophore in outer region of its base. Eyes dark, smali. Female with ovopositor in right region of foot described below. Operculum (fig. 67) with sub-terminal nucleus. Other characters see Marcus & Marcus (1964: 498-500). Sevcral specimens with a broad furrow in middle region of columellar muscle (fig 315: hl)

Pallial cavity (figs 317, 318, 321). Mantle borderentirely with single lined, similar sized smali papillae. Osphradium bipectinate, very long, with about same gili length, two regions differentiable: anterior half broader and somewhat sinuous, pos-terior half narrower. Osphradium in transversal cut with a longitudinal narrow axis and several very smali rounded leaflets, disposed intercalated (fig. 318). Mantle, in siphonal region, with thicker walls. Fold anterior to gili, perpendicular to border, forming a septum (h2). Gili very long, narrow, filaments tali, triangular, tip pointed, finishes before posterior limit of cavity. Other characters in Marcus & Marcus (1964: 500-501).

Circulatory and excretory systems (fig. 321). Heart as described for preceding species, anterior and posterior aortas attached to style sac and intestine. Kidney with single lobe. A well developed posterior renal vessel from which several transversal secondary vessels begin within glan-dular white tissue. A thickness of glandular tissue around its wali with pericardium. Pallial region of kidney solid, with radial fuiiows. Nephrostome a single slit in middle region of wali between kidney and pallial cavity.

Digestive system (figs 319-328). Buccal mass in anterior half of snout. Jaws of considerable size, from which two dorsal folds begin, run longitudinally in dorsal inner surface of buccal mass; aperture of salivary glands in they middle region. Odontophore (figs 326-328) similar to described for preceding species, distinctive features: 1) m8 absent; 2) m2 narrow and with some anterior fibers inserted in m4; 3) mil not inserted in cartilages, and neither in anterior region of peribuccal wali; 4) m7 with origin part in ml 1 and part in adjacent region of subradular membranę; 5) m5 somewhat narrow and anteriorized. A pair of dark spots in dorsal region of cartilages (figs 322, 325: ds), remainder of cartilages white. Radularteeth (figs 100,101): rachidian tooth short and broad, with 5 cusps, central cusp very larger (about three times the neighbors) and a Iow, triangular, central, basal projection; lateral tooth with 5 cusps being second cusp very larger, morę than 3 times the neighbors; marginal teeth spoon-like, with a rounded cut-edge and two smali cusps in inner region of this edge; inner and outer marginal teeth very similar with each other. Left salivary gland smali, attached to posterior region of nerve ring, right salivary gland long, large, begins in right-posterior side of nerve ring, towards left and runs in left side of middle esophagus (figs 319, 320).