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Vol. 36(2), 2001

Description.

Shell (figs 27, 28,48). Smali (up to 10 mm) slender, turriform, up to nine whorls. Periostracum opaque, yellowish, transparent. Two first whorls smooth (fig. 48), gradually axial and spiral threads appear, both predominating; in they intersection smali nodes; these nodes generally paler than remainder shell and variable in size according to specimen, in some specimen very smali nodes, in other very large nodes, long in spiral axis and sometimes coalescent. Spiral threads varying from 4 to 4 in pcnultimate whorl. A large axial thread generally present in dorsal region of last whorl. Outer lip deflected, canal smali. Color elear beige with brown spots scarce and sparse; in some specimens these spots greater; sometimes entire shell dark brown. Other details see Marcus & Marcus (1963: 74-76). When decalcified, inner chitinous layer visible, pale brown, transparent (fig. 335: ic).

Head-foot (figs 329, 330, 332, 333). Pigmented by a mosaic of dark spots, sometimes Coalescent, inclusive in pedał sole. Head protruding. Snout sub-cylindrical, relatively smali (about 2/3 of tentacles length), bilobed anterior margin.Tentacles long, with dark eyes in they base without ommatophore. Foot very large, about 1/3 whorl, two parallel Iow furrows run between mesopodium and metapodium. A deep longitudi-nal furrow in posterior half of mesopodian sole. Female with a well developed ovopositor in right side of foot described bclow. Columellar muscle of about one whorl. Other details see Marcus & Marcus (1963: 76-78, fig. 80).

Operculum (fig. 64). Yellowish, semi-transparent, circular, palcispiral, sub-central nucleus, occupies almost entire aperture. Scar broad, circular, near inner margin.

Pallial oigans (figs 331, 334, 335). Mantle border flanged by short, broad, flattened papillae. Pallial cavity of about 1.5 whorls. Osphradium of about same length than gili, pectinate, brown pigmented. Satellite osphradium fold thin, white, surrounds anterior limit and both sides of it; about same length than osphradium in each side. Gili long, begins at some distance from mantle border, filaments triangular, somewhat tali. Between gili and rectum a relatively narrow space. Hypobranchial gland thin, in posterior half of this space. Rectum and genital ducts in right margin, described below. Anus siphoned relatively posterior of mantle edge. Other details in Marcus & Marcus (1963: 78-80, fig. 88).

Circulatory and excrctory Systems (fig. 334). Heart laige, with characters similar to those of preceding species. Kidney white in color, short (about 1/12 whorl), with single lobe. Lobe solid, flattened between style sac and pallial cavity. Nephrostome smali, near right region of membranę between kidney and pallial cavity.

Digestive system (figs 78, 332, 334, 337-344). Mouth longitudinal, situated within snout anterior furrow. Jaws (fig. 78) two proportionally large and broad plates. Buccal mass relatively posterior in snout. Inner surface of dorsal wali of buccal mass with two longitudinal folds (fig. 339), beginning in jaws; very broad in middle region presenting each one a median longitudinal furrow. Odontophore (figs 342-344) similar to those of preceding species but short, with horizontal muscle very broad and short; radular sac short ventrally attached to dorsal wali of esophagus; mil connected with anterior region of cartilages and running only to m7, without connection with peribuccal region. Radular teeth (figs 102, 103): rachidian tooth with 7 and sometimes 9 cusps being central cusp larger, a smali long projcction in each side of its base; lateral tooth with 5 cusps being second cusp larger; inner marginal tooth rook-like, with 5 cusp in each side of its ffee region; outer marginal tooth similar to inner marginal but narrower. Salivary glands posterior-dorsal to nerve ring, with ducts running through nerve ring and inserting in dorsal wali of buccal mass. Anterior esophagus with 4 folds, ventral folds larger, originate from folds of dorsal wali of buccal mass; pigmented by brown, easily seen by transparency (fig. 338). Middle esophagus with 4 similar sized folds, twisted in relation to anterior esophagus. No apparent glands in esophagus. Stornach (figs 340, 341) as described by Marcus & Marcus (1963: 81, fig. 83) with well developed dorsal sorting area; gastric shield protruding; central pad smali; crescentic ridge similar to central pad, subcircular and posterior to it; style sac short (about 1/4 of stornach length), connected with intestine by a furrow; style present. Rectum relatively short and narrow, with several fecal pellets obliquely disposed. Other details of digestive system in Marcus & Marcus (1963: 82-87).

Genital system. Małe (figs 334, 336).