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Arquivos de Zoologia

wali with two inner longitudinal folds. Jaw plates very thin and transparent, situated in anterior region of dorsal folds. Odontophore smali, with following distinctive features: 1) ml (jugal muscles) and mlO pairs very developed in ventral margin, with broad fibers tumed anteriorly and other narrower tumed posteriorly (m3d); 2) m2 absent; 3) m4 with fibers no only connected to tissue on middle region of radular ribbon, but also with its posterior region and even with radular nucleus; 4) m5 short, 5) m8 and m9 absent. Radula very short and narrow. Radular teeth (fig. 97): narrow, long, similar sized cusps in free maigins of all teeth; rachidian tooth with 21 cusps in pointed cut edge; lateral tooth with about 16 cusp in each side of its pointed edge; marginal teeth rook-like, with about 20 cusps in each side of they free region; outer marginal tooth discretely morę curved than inner one. Salivary glands smali, posterior to nerve ring, ducts through it. Esophagus very long, narrow, thin walled. Esophageal inner surface with 2 almost vestigial crops, with obliąue smali folds (fig. 291). Right crop only visible in lateral region of a large fold. Left crop larger. Other posterior regions of esophagus only with Iow, wel l spaced, longitudinal folds.

Stornach (figs 284, 288) occupying about half a whorl, separates almost completely digestive-gonad glands ffom pericardial-pallial structures. Internally divided, by a constriction, into 2 chambers. Posterior chamber larger, bearing esophageal aperture at left and a large fold at right, this a central-pad-like structure which covers single duet to digestivc gland; other regions smooth. Anterior chamber with smooth surface, two apertures as anterior limit connected with each other; larger that of style sac; smaller, at left, that of intestine. Style sac relatively large, about half of remainder stornach length, cylindrical, covered intemaliy by yellowish iridescent chitin. Style present. Intestine (fig. 284) beginning opened to style sac, afterwards becoming a tubę, contours to right side of style sac, crosses vcntrally kidney and emerges in right side of pallial cavity. Rectum broad, bearing several fecal pellets obliąuely disposed. Anus upper described. Digestive gland green, occupying about two whorls (keeps empty first shell whorls).

Genital system. Małe (figs 285,286). Testis smali, in peri-columellar region of digestive gland. Vas deferens runs close to columella, white and narrow. In right side of posterior limit of pallial

cavity, spermoduct suddenly expands, after short distance opens and becomes a groove with thick glandular walls (prostatę); no differentiable inner structures. Sperm groove long, lies almost entire pallial cavity right margin, finishes posterior to anus.

Female (figs 283, 294, 295, 298). Ovary smali, pale gray, in peri-columellar region of digestive gland. Oviduct white and narrow, runs close to columella. In right side of posterior limit of pallial cavity, oviduct suddenly expands and becomes a wide, thin walled tubę (fig. 294). Bursa copulatrix a sac attached to inner ventral surface of posterior region of pallial oviduct, with narrow anterior aperture. Seminal receptacle similar to bursa, attached to inner dorsal surface, in opposite side of bursa. Capsule-albumen glands difficult in being separated one another, a smali glandular mass covering receptacle and part of adjacent inner dorsal surface of oviduct. After a short distance, pallial oviduct opens, becoming a groove with very thin transparent walls, lies to region posterior to anus. Ovopositor in right region of head-foot, a transver-sal elevation of clearer colored muscles close to columellar muscle, and a nodular projection in same level, but near food groove (fig. 283).

Where pallial oviduct opens (fig. 294: ap), j capsules exit and stay in pallial cavity. From 10 to 12 large capsules aligned along pallial cavity in maturę females (fig. 298). Capsules compress greatly pallial structures, mainly gili, such filaments fit between capsules.

Capsules (figs 296-298). Proportionally large, diameter almost 1 mm, rounded, somewhat flattened. Covered by hard, yellow, glossy membranę (fig. 296). From 2 to 5 young specimens in each capsule having one whorl each (fig, 297). Some undeveloped eggs also commonly occur. Young specimens immersed in yellow jelly-like mucus.

Measurements (in mm). 19.5 by 5.1 (figured specimen); 24.0 by 6.6.

Distribution. From Rio de Janeiro to Sao Paulo Continental slope.

Habitat. Sandy bottoms, from 10 to 156 m depth (MZSP 19417, only shells).

Materiał examined. Brazil; Rio de Janeiro; off Campos Bay (R. V. Astrogaroupa, sandy bottom); 22°35’47”S 41°55’01”W, 20 m, MZSP 28387,1 d; 22°05’ 15”S 40°45”05”W, 35 m, MZSP 28388, Id¹ (23/vii/l991); 22°47’01 ”S 41°30’21 ”W, 57 m, MZSP 28389, 19 (iii/1992).