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Arquivos de Zoologia

in end of pallial cavity; left limit the style sac (dorsally) and kidney (ventrally), right limit the anterior extremity of gonad and columellar muscle, firom which anterior aorta attaches. Kidney long (about half whorl) but narrow, runs at right of style sac; with single lobe, solid, yellow. Membranę between kidney and pallial cavity smali, with nephrostome at right close rectum.

Digestive system (figs 392, 395-403). Mouth in anterior extremity of snout, longitudinal, ventral, thickly muscular. Buccal mass part within snout. Jaws two thin triangular plates, cut edge in anterior and median bordeTS. Inner surface of buccal mass dorsal wali (fig. 397) with two longitudinal broad and Iow folds, beginning from each jaw; aperture of salivary ducts in middle region of inner margin of each fold. Odontophore muscles (figs 400-403) similar to those of preceding species, with following distinctive features: 1) m4 and m5 connected with each other in a higher degree, almost all outer border of m5 attached to ventral region of m4; 2) m4 posteriorly inserted in tissue covering middle region of radula; 3) mil pair originating in middle-inner region of subradular membranę, with 3 anterior insertions: a narrow connections to anterior extremity of cartilages, other originating m7 and other running anteriorly to peribuccal muscles (fig. 403); 4) m8 absent. Radula short, forming a “S”. Radular nucleus flattened and thick. Radular teeth (figs 109-110): rachidian tooth of somewhat rounded outline, with nine cusps, being central cusp larger, no basal cusp; lateral tooth with 5 cusp being second lager and terminal; inner maiginal tooth spoon-like, with 3 terminal cusps being lateral cusp larger; outer mar-ginal tooth similar to inner one, but with 5-6 smaller cusps. Esophagus single, long and narrow, with 2-3 Iow longitudinal folds, no visible glands. Stornach large, occupies half whorl excluding style sac. Stornach (figs 395, 396, 398, 399) with 2 inner chambers separated with each other by a constriction. Posterior chamber longer, central pad long, duet to digestive gland in middle region of left border of central pad; crescentic ridge surrounds this duet and contours posterior half of central pad; esophageal aperture simple, in middle of left side of stornach. Apertures of intestine and style sac as anterior limit of stornach, united one another by a very short distance. Style sac cylindrical, very long - about half whorl, arriving

in level of posterior region of pallial cavity (figs 395, 396). Intestine narrow, almost entirely free from style sac; contours ventrally style sac from left to right side, where there is other loop to right; in pallial cavity suddenly expands. Rectum and anus described above.

Genital system. Gonad, in both małe and female, occupying superior and extemal surface of each whorl, on digestive gland; when maturę, runs ventrally and at right stornach and style sac, arriving in level of posterior region of pallial cavity, at left of posterior half of style sac (figs 395, 396). Visceral gonoduct runs close columella, a thick walled duet; in pallial cavity expands. Małe pallial sperm groove (fig. 405) almost entire opened and thick glandular, no special inner structures except a longitudinal, medial fold in its posterior extremity (fig. 405: n2). Female pallial oviduct (fig. 404) also almost entirely opened and thick glandular; bursa copulatrix sac-like, situated in posterior region of inner lamina border, opens anteriorly in a groove, | which runs in remainder length of inner lamina , border; no other differentiable structure. Pallial oviduct finishes in a right furrow of head; this furrow runs ventrally until near sole, and surrounds posterior-ventrally ovopositor. Ovopositor (fig. 391) a somewhat triangular thickness of right- ! dorsal region of foot, with dorsal limit imprecise. i

Measurements (in mm). 18.8 by 5.4; 15.1 | by 4.7 (figured specimens); 12.8 by 4.8; MZSP > 28264: 9.6 by 4.0.    |

Distribution. Florida to South Caribbean. i

Habitat. Estuanne environment, moving on t mud or on root of trees. in generał with a cover of cellulose, brown, around entire shell, only aperture was free (fig. 40).

Materiał examined. Venezuela; Nova i Esparta; Margarita Island; Porlamar city, Caracola estuary, MZSP 28263, 36 specimens (30/1/1996, Simone col.); La Restinga, Central beach, MZSP 28264, 19 specimens.

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Remarks. In early papers, species of the genera ! Cerithidea and Batillaria, were grouped within the j family Potamididae. Morę recently, Houbrick (1988: 89), based on anatomical differences, separated each genus in a family proper: Cerithideidae and Batillariidae respectively, both ( separated from Potamididae. In that paper, the author referred, however, that maybe Cerithideidae