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162

Arquivos de Zoologia

versal folds with irregulai surface; anterior region with area about twice longer than posterior one, bearing severa) transversal folds attached to rectum surface, somewhat Iow and well spaced one another, these folds are present even outside nephrostome. Nephrostome a broad aperture between rectum and anterior kidney region, protected at left by a solid flap, with 4-5 folds, similar to that of preceding species, inclusive insertion in outer lamina of pallial gonoduct (figs 226, 232).

Digestive system (figs 229-231, 236-243). Buccal mass of medium size, situated almost entirc within snout. Jugal muscles similar to those of preceding species except by a large development of a pair (figs 237, 239, 240: ml6), denominated lateral dilator of mouth, origin in lateral-anterior inner surface of snout, insert in anterior-lateral region of peri-buccal muscular mass, being somc fibers inserted directly in pad where jaws connect. Jaws (figs 77,239) somewhat large and broad, cut edge rounded. Inner surface of dorsal wali of buccal mass with 4 folds in anterior extrcmity, two of them larger, connected in jaws, and two narrow running laterally; after some distance lateral and jaw fold fuses one another, originating a pair of broad dorsal folds which run to esophagus; between both folds a broad, thin walled furrow. Aperture of duet of salivary glands in middle and outer margin of dorsal folds. Pair of m2 distinct in having origin anterior in haemocoel lateral inner surface, being tumed anteriorly in retracted condition. Odontophore distinctive features (figs 241-243): 1) ml5 developed; 2) mil pair originated in inner-anteri-or surface of subradular membranę, near its dctachment of subradular membranę (anterioly) bear two pairs of smali muscles, dorsal pair vcry narrow, connectcd with anterior extremity of cartilages, ventral pair narrow, connected with radular ribbon, intemally to radular sac; afterwards, mil tum anterior-ventrally and inserts in dorsal region of transition snout-foot, close to radular sac; in this site bear a pair of smali and short muscles connected to extema! side of radular sac; 3) m8 very long and narrow; 4) mlO posterior inserted, close m4. Asymmetry of odontophore (figs 241, 242) shown in all examined specimens (right sidc morę anterior than łeft side). Radular ribbon very long, coiled in its posterior region. Radula (figs 91, 92) similar to that of preceding species, rachidian tooth with 7 cusps, being central cusp larger (about double); lateral tooth with 5 cups, third cusp larger; inner marginal tooth long and broad, with 3 broad terminal cusps; outer marginal tooth rook-like, rounded apex. Salivary glands large, run dorsally from region near m2 to anterior esophagus, where twist ventrally and run to region of nerve ring, not passing through it. Anterior esophagus (figs 236-239) with about five folds in dorsal side, being both marginal folds tali and fiat. Middle esophagus with single pouch, large, with inner surface complctely covered by somewhat tali papillae; tali folds of anterior esophagus become Iow in middle esophagus, but taller than 3 or 4 smali folds which run between them; this group of folds runs paralle! one another in ventral side of pouch. Posterior esophagus narrower, with 5 to 6 Iow, slightly uniform, longitudinal folds. Stornach (figs 229,230) with little less than a half whorl, intemally very complex. Dorsal wali with 3 differentiated sorting areas, two smali anterior and a larger in pos-terior-right side; among these sorting areas 2 semi-circular, thick folds with lobed edge, concavity an-terior-right; other fold, narrow, edging at right posterior sorting area and contours right extremity of thick folds. Gastric shicld well developed. Central pad with about a third of ventral gastric area and divided in three lobes by transversal furrows, anterior lobe close shield, middle lobe with duet to digestive gland in its left maigin, and posterior lobe bulged and covered by a mosaic of “U” shaped acina. Crescentic ridge edging at some distance posterior lobe of central pad, connected with it at right. Esophageal aperture simple, near duet to digestive gland. Anterior gastric chamber short; a large but short fold in intestine origin present, with transversal successive furrows in its edge. Digestive gland begins in middle-ventral region of stornach and has l .5 whorls posterior to it. Intestine opened to style sac in almost its entire left side (fig. 231), but separated from it by a constriction. Intestine, after separation with style sac, contours it and arrives in its posterior right region; after a loop return to anterior where exits to pallial cavity. Rectum and anus above described.

Genital system (figs 233-235). Both, masculine and feminine genital Systems similar with each other. Gonad in superior region of digestive gland. Visceral gonoduct run close columella, a thick walled narrow duet. In right-posterior region of pallial cavity emerges and