. Bulletin of the Natural History Museum Zoology. 60 KANTOR, A. MEDINSKAYA AND TAYLOR Crassispira (Gibbaspira) dysoni (Reeve, 1846) (Figs 4c, 5) Rhynchodeum and proboscis The rhynchostomal sphincter is medium-sized and anteriorly lo- cated. The epithelium of the anterior half of the rhynchodeal wall is tall and glandular, while the posterior half is continuous with that of the proboscis wall. The proboscis tip is not inverted. The proboscis is short (about half of the rhynchocoel), not coiled, but slightly folded and narrowing towards the tip. The muscles of the proboscis wall are eq
. Bulletin of the Natural History Museum Zoology. 60 KANTOR, A. MEDINSKAYA AND TAYLOR Crassispira (Gibbaspira) dysoni (Reeve, 1846) (Figs 4c, 5) Rhynchodeum and proboscis The rhynchostomal sphincter is medium-sized and anteriorly lo- cated. The epithelium of the anterior half of the rhynchodeal wall is tall and glandular, while the posterior half is continuous with that of the proboscis wall. The proboscis tip is not inverted. The proboscis is short (about half of the rhynchocoel), not coiled, but slightly folded and narrowing towards the tip. The muscles of the proboscis wall are equally developed along its length. The anterior buccal tube sphincter is small, whilst the sac-like enlargement of the buccal tube is long, with a long epithelial pad, formed of large cubic cells with large nuclei. At the base of the enlargement, there is an intermediate sphincter, which lies at a distance of three radular tooth lengths from the mouth. The walls of the sac-like enlargement are thicker than the rest of the buccal tube and similar to those of C. (Crassiclava) spp. The buccal tube is lined with ciliated epithelium. The proboscis wall is thin, form- ing about 10% of the proboscis diameter, while the wall of the buccal tube comprises about 7% of proboscis diameter. Buccal lips are absent. Buccal mass and oesophagus The buccal mass lies to the posterior of the proboscis, and is small, thin-walled and curved, and comprises less than one fifth of the proboscis length. The oesophagus is greatly elongated between the buccal mass and nerve ring and forms a long loop. The epithelium bears very long cilia, which occupy nearly the whole lumen. The opening of the radular diverticulum into the buccal cavity is quite narrow and bordered by a rather tall circular muscular fold, similar to that seen in C. harfordiana. The salivary ducts open into the radular sac at the base of this fold (Fig. 5). Glands The salivary glands are large and acinous, with ducts that are thick, very lon
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Keywords: ., bh, bookcentury1900, bookcollectionbiodiversity, bookleafnumber62
