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but some variation occurs in same ribbon; outer marginal tooth similar to inner one but narrower and with 3 cusps generally same sized. Salivary glands clusteraround esophagus just posterior to nerve ring, have two lateral expansions being left one longer. Esophagus nairow (fig. 212), ventral region with two parallcl typhlosoles. Esophageal pouch single, large, with inner surface replete of many tali papillae; occupies anterior and middle esophagus (fig. 215). Posterior esophagus with 5 to 6 longitudinal, similar sized folds. Stornach large, about half whorl (fig. 216). Central pad relatively smali, duet to digestive gland in middle region of its left margin. Crescentic ridge smali, surrounding at some distance posterior region of central pad. Gastric shield smali, in anteri-or-right side of central pad; dorsal sorting area elliptical, surrounded by smooth areas. Intestine and style sac united one another in almost they entire left region, separated only by a constriction. Intestine nanow, with single loop in right side of style sac. Rectum broad, with several fecal pellets obliąuely compacted. Anus described above.

Genital system (figs 213, 214). Małe and female genital organs similar. Gonad in superior region of first whorls, on digestive gland. Visceral gonoduct close columella. Pallial gonoduct almost entire opened, simple, without chambers or annex structures cxcept a cxpansion covering nephrostome, connected to posterior extremity of outer lamina (fn). Pallial gonoduct finishes posterior to anus. No ovopositor differentiable.

Measurements (in mm). Holotype: 24.4 by 11.2 (figured specimen); MZSP 28688: 26.0 by 12.3; MZSP 28690: 23.8 by 11.9.

Distribution. Only known from type locality.

Etymology. The specific epithet “ipupiara”, from Amazonian Tupy language, means a entity who lives under water (Cascudo, 1962).

Doryssa atra (Bruguiere, 1792)

(Figs 14. 59,77,91,92,225-544)

Synonymy see Tillier, 1980: 14.

Complement: Doryssa atra: Morretes, 1949: 75.

Description.

Shell (fig. 14). Large, very long, dark brown; whorls discretely convex. Axial sculpture present in first whorls, gradually disappear, last whorls only with spiral sculpture (about 10 in penultimate whorl). Peristome cream in color, with some sparse dark brown spots. Other details in Tillier (1980: 14, pl. 1, fig. 1).

Head-foot (figs 225,236). Color dark brown with some clearer spots, of imprecise borders, sparse in integument; this color gradually becomes paler up to posterior regions of head. Head protmding. Snout large, broad, somewhat short, dorso-ventTally flattened; anterior margin multilobed. Mouth longitudinal, antero-ventral and thickly muscular; most of ventral-anterior snout folds converge to mouth. Tentacles stubby, ommatophore in they basal outer region sessile in head. Eyes dark, proportionally smali, in anterior-dorsal region of ommatophores. Foot of medium size, without divisions; anterior furrow of pedał glands; a smali mesopodial tentacle in posterior extreme of foot. Columellar musclc of about J .5 whorls.

Operculum (fig. 59). Similar to that of preceding species.

Mantle organs (figs 226-228, 232). Mantle border simple, without neither tentacles nor papillae. Mantle cavity of about two whorls. Siphon inconspicuous. Osphradium long, ridge-like, with about half of gili length; anterior and posterior than that of gili, and preceded by a zigzag. Gili narTOW and long, about same length than pallial cavity, filaments triangular, Iow; tip rounded, almost central. Ctenidial vein well developed, without large dilatation. Between gili and rectum a relatively broad area with some transversal, sparse vessels. Hypobranchial gland inconspicuous. Adrectal sinus around entire rectum, but little evident. Rectum broad, with fecal pellets obliąuely disposed. Anus siphoned near mantle border. Genital ducts in right margin described below.

Circulatory and excretory systems (figs 226, 231, 232). Heart characters similar to those of preceding species, with aortas attached to anterior region of style sac and adjacent intestine. Kidney short, about 1/6 whorl; almost entire solid, except a chamber surrounding its connection with rectum; inner surface of this chambers as follows (fig. 226): at left covered by several tali septa; these septa thin, somewhat uniform, smooth, dark brown except they free vertex which are elear beige and thicker; these septa gradually fuse one another in left kidney region in a massive, radial furrowed tissue, mainly situated in pallial cavity; at right two regions: posterior region free from rectum bearing tali, trans-