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Vol. 36(2), 2001

extremity of mantle border, posterior to end of pallial oviduct. Pallial oviduct runs along right side of pallial cavity.

Circulatory and excretory systems (figs 117, 119,120). Heart large, situated posteriorly in pallial cavity behind gili, auricle large and anterior, ventricle spherical, smali and posterior. Aorta runs attached to style sac, large anterior aorta on left; very thin and narrow posterior aorta on right. Kidney pale cream, proportionally large, occupying about half a whorl, situated at posterior-right limit of pallial cavity. Kidney composed of two lobes: posterior lobc larger, attached to right surface of intestine, solid, glandular, with several smali vessels connected to a larger central and longitudi-nal vessel, bulges on right into pericardium chamber and anteriorly into pallial cavity; anterior lobe smaller, attached to left surface of rectum, hollow, with successive transverse folds inserted in a central, longitudinal, larger vessel (fig. 120). Nephrostome a slit in right extremity of membranę between kidney and pallial cavity, close rectum.

Digestive system (figs 117, 119, 122-135). Mouth lies at anterior extremity of snout, longitudinal, ventral, thickly muscular. Buccal mass lies within snout just behind mouth (figs 122, 123); esophagus dorsal, odontophore ventral. Jaws consists of two plates, anterior and median borders with irregular cut-edges (figs 72,128), lateral edges rounded. Two longitudinal folds begin from jaws and run towards posterior. Salivary ducts open near two smali protuberances in middle region of longitudinal folds in inner-dorsal region of buccal cavity (fig. 128). Odontophore with an atypical muscle arrangement (fig. 125-132): ml) jugal muscles, several differentiated muscles around buccal mass anterior region, with their origin in inner face of buccal wali and snout; m2) pair of large retractor muscle of buccal mass (pharynx), origin in inner surface of lateral haemocoel wali, at side of esophagus, insertion in lateral surface of buccal mass, mainly on its dorsal wali, only some fibers inserted in odontophore; m3) pair of smali ventral retractor muscle of odontophore, origin in dorsal region of foot ventral to esophagus, insertion in middle-ventral region of odontophore surface; m4) pair of lateral compressor tensor of radula, origin attached to anterior and lateral regions of cartilages, surrounding ventrally each cartilage, keep free only median surface of cartilages, insertions of jaws and peri-buccal muscles (ji); in dorsal surface of each m4 a thin, but strong subradular membranę inserts, which subradular cartilage attaches; this membranę bears a region sharply bulged, anterior to subradular cartilage; m4 also inserts in a tissue covering middle and dorsal region of radular ribbon (tr); m5) pair of middle ventral tensor of radula, origin in anterior outer surface of m4, surround inner ventral and median faces of m4, insertion in middle region of subradular cartilage, in level and below of m4 insertion in tissue on radula (tr); m6) horizontal muscle, short and broad, insertion in lateral-dorsal region of each cartilage; m7) anterior-ventral tensor muscle of radula, smali and thin, origin part in ml 1 muscle, and part in adjacent region of subradular membranę, insertion in ventral-middle region of radular sac; with m7 also runs a hollow diverticle from radular sac (di), probably a sinus of anterior aorta; mlO) pair of odontophore protractor, origin in ventral-median region of peribuccal wali, insertion in ventral-anterior region of odontophore, in m5 surface; mil) pair of dorsal middle tensor muscle, very thin, origin in middle inner region of subradular membranę, insertion in ventral region of peribuccal wali; ml2) pair of dorsal compressor of cartilages, thin and narrow, origin in anterior extremity of cartilages, insertion in dorsal margin of cartilages near horizontal muscle origin. Radula short, forming a “S”. Radular nucleus flattened and thick. Radula (figs 82-83): rachidian teeth with seven cusp upper and nonę down. Lateral teeth long, with seven cusp being third larger. Both mar-ginal teeth similar one another, long, curved, spoon-like, with seven broad cusps; inner marginal teeth discretely broader than the outer marginal teeth. Organization of digestive tubę between odontophore and esophagus similar to a valve, bearing attached a tali fold (fig. 128: to). Esophagus simple, long, narrow. Anterior esophagus with two Iow longitudinal folds in its inner dorsal side (fig. 128). Posterior esophagus very narrow, without inner folds. Pair of buccal ganglion in posterior region of buccal mass, close to insertion of m2 muscle, large, white, connected one another by a median connective (fig. 127).

Stornach large andcomplex (figs 134,135), separates almost completeiy digestive-gonad glands from pericardial and pallial structures, occupies about half whorl. Stornach intemally with