. Bulletin of the Natural History Museum Zoology. FOREGUT ANATOMY OF CRASSISPIRINE GASTROPODS 57 pt proboscis tip rh/rhc rhynchocoel rhs rhynchostomal sphincter rs radular sac rst rhynchostome rtsg anastomosing tubular salivary gland rw rhynchodeal wall rwg rhynchodeal wall glandular sd salivary duct se sac-like enlargement of buccal tube sg salivary gland stag single tube acinous salivary gland t radular tooth. tsg simple tubular salivary gland V valvule vg venom gland vga duct of venom gland In this section we describe and illustrate the foregut anatomy and radulae of each of the species exa
. Bulletin of the Natural History Museum Zoology. FOREGUT ANATOMY OF CRASSISPIRINE GASTROPODS 57 pt proboscis tip rh/rhc rhynchocoel rhs rhynchostomal sphincter rs radular sac rst rhynchostome rtsg anastomosing tubular salivary gland rw rhynchodeal wall rwg rhynchodeal wall glandular sd salivary duct se sac-like enlargement of buccal tube sg salivary gland stag single tube acinous salivary gland t radular tooth. tsg simple tubular salivary gland V valvule vg venom gland vga duct of venom gland In this section we describe and illustrate the foregut anatomy and radulae of each of the species examined. The terminology of the anatomical characters and organs largely follows Taylor et ai, (1993). Most of the features are illustrated diagrammatically in Fig. 1, with details of others given in the descriptions of individual species. Crassispira (Crassispira) incrassata (Sowerby, 1834) (Figs 2, 4a) Rhynchodeum and proboscis The rhynchostomal sphincter is large and located in a slightly posterior position. The epithelium of the posterior rhynchodeal wall. lmb Fig. 1 Composite diagram of the foregut of a hypothetical crassispirine gastropod, showing the location of the major structures discussed in the text. No single species has all these structures. is continuous with that of the proboscis wall for slightly more than half the length of the rhynchodeum. Extremely large proboscis retractor muscles are attached to the rhynchodeum at the border between the two different epithelia and at the proximal ends to the columellar muscle. The proboscis is long (more than half of the rhynchodeum), slightly narrowing towards the tip. The proboscis tip is not inverted inside. The muscles of the proboscis wall in the posterior two thirds of the proboscis are significantly thicker than in the anterior section. The proboscis lies coiled within the rhynchocoel (shown uncoiled in drawing to illustrate relative proboscis length). There are two ante- rior buccal tube sphincters. A sac-like enlarg
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