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3) presence of the nephiostome. On the other hand, what allow a ftinction as an ureter of this chamber are the following data: 1) the presence, almost indistinguishable, in both sexc s; 2) its development even in young specimens with remainder genital system until incipient; and 3) its anatomical disposition, connecting kidney chamber with region closer to mantle border (morę deve!oped in Doryssa thmPachychilus). Anyway, a similar structure is not found in any other studied gastropod beyond pleurocerids. This character was probably lost in D. ipupiara.

Woodart (1934) described the genital system of the pleurocerid Goniobasis laąueata (Say). The pallia) oviduct of this species has a short and broad seminal receptaclc, apparently in the same localization of the bursa of the examincd species. The seminal receptacle naturę of the structure of G. laąueata was confirmed histologically by that author, presenting sperms.

Family Turritellidae Genus Turritella Lamarck, 1799 (Type species: Turbo terebra Linne, 1758)

Turritella hookeri Reeve, 1849

(Figs 20, 62, 97, 287-298)

Turritella hookeri Reeve, 1849 (pl. 11, fig. 61); Kobeit, 1897: 29 (pl. 6, fig. 11); Rios, 1970: 37 (pl. 9); Abbott, 1974: 95; Rios, 1975: 44 (pl. 12, f. 159); 1985:46 (pl. 18, f. 206); 1994: 65 (pl. 22, f.248).

Descńption.

Shell (fig. 20). Of medium size (up to 40 mm), white, turriform. Protoconch of one whorl, smooth, glossy, carinate in periphery. Teleoconch up to 12 whorls, opaque, sculptured by two strong spiral threads and growth lines. Aperture simple, circular, without canal or projections. Other details inReeve(1849).

Head-foot (figs 282, 283, 287, 298). Homogeneous pale beige in color. Head protruding, relatively smali. Snout proportionally smali, cylindrical, strongly bilobed in antero-ventral margin. Tentacles stubby, somewhat long. Eyes dark in outer region of tentacles’ base, without ommatophore. Foot proportionally large, without divisions. Anterior fijrrow of pedał glands deep. Coiumellar muscle long, firom 3 to 4 whorls. Food groove well developed, with thick walls, in median posterior region of floor of pallial cavity sińce its beginning, contours right side of head and finishes in median-ventral region of snoufs base. Wall behind head very thick muscular.

Operculum (fig. 62). Circular, multispiral, comeous, nucleus central, occupies entire aperture, fimbriated edge. Muscle scar elliptic near inner margin.

Mantle organs (figs 285, 286, 294, 298). Mantle border of homogeneous pale beige color, entirely with smali, uniform, relatively long papillae. Right insertion of mantle border very posterior, just in a richly muscular elevation behind head. Mantle cavity of almost three whorls. Osphradium difficulty visible, immerse in endostyle. Endostyle (figs 285,286: f2) lies almost entire left margin of pallial cavity on ctenidial vcin, anatomically leaned in food groove. Gili with about same length than cavity; filaments very tali, trian-gular, except in both extremities, where gradually become Iow; tip pointed. Relatively long posterior region of ctenidial vcin free from gili. Between gili and rectum a relatively broad space. Hypobranchial gland white, thin, mainly developed in posterior 2/ 3 of cavity. Rectum broad and long. Anus siphoned, tali, posterior situated. A large fold from anus to near mantle border, perpendicular to this (fig. 286: fl). Pallial gonoducts long and nanow, compressed between rectum and right margin of mantle cavity, described below.

Circulatory and excretory systems (figs 284, 286, 294). Pericardial cavity posterior to kidney, connected to anterior region of style sac. Anterior and posterior aortas run attached to style sac. Anterior aorta very broad, runs parallel to esophagus up to buccal mass. Kidney short, situated in poste-rior-right limit of pallial cavity. Kidney with single lobc, color white, intemally solid (without hollow chambers); bulges anteriorly to pallial cavity in a form of a tali elevation. Nephrostome a slit in median region of membranę between kidney and pallial cavity.

Digestive system (figs 284,287-294). Mouth longitudinal and ventral, deeply introduced in snout antero-ventral furrow. Buccal mass very narrow, part within snout and part in head. Dorsal buccal mass