FOREGUT ANATOMY OF CRASSISPIRINE GASTROPODS 



75 



layer. The epithelium, lining the inner cavity is rather well-devel- 

 oped in one specimen, but non-glandular. 



Odontophore and radula 



The odontophore is medium-sized with paired, unfused odontophoral 

 cartilages. A buccal sac is absent. The radula (Fig. 1 7d) consists of 

 marginal teeth which are of the wishbone type with a robust major 

 limb and a smaller secondary limb. The marginal tooth is short, 

 ca. 140pm (0.5% of SL, 1.4% AL). 



Funa jeffreysii (Smith, 1875) 



(Figs 19, 23d) 



See also Taylor (1994, plates If, 6a; figs 8 & 9) 



Rhynchodeum and proboscis 



The rhynchodeal sphincter is large and anteriorly located. The 

 epithelium of the anterior one third of the rhynchodeum is highly 

 folded and glandular, formed of large cells. In the posterior of the 

 rhynchodeum there is an abrupt change to a very low and incon- 

 spicuous, non-glandular epithelium which is continuous with that of 

 the proboscis wall. 



The proboscis is long, as long as the rhynchodeum, with the tip 

 not infolded. The proboscis walls are thin, comprising about 7% of 

 proboscis diameter. The walls of the buccal tube are similarly thin, 

 composing about 5% of total diameter. The mouth is narrow. The 

 muscles of the proboscis walls are equally developed along its 

 length. 



There is a medium-sized, anterior buccal tube sphincter, posi- 

 tioned at the base of the sac-like enlargement of the buccal tube. An 

 epithelial pad is present within the sac-like enlargement. There is no 

 intermediate buccal tube sphincter. The buccal tube is lined with a 

 very low epithelium. It expands greatly to form a long circular fold, 

 which appears like poorly-muscularized, anteriorly-directed lips, 

 similar to the 'valvule' (Sheridan et al, 1973) The buccal lips are 

 large and muscular. 



Buccal mass and oesophagus 



The buccal mass is large and situated partially within the proboscis 

 base. Its walls are moderately thick. The oesophagus is greatly 

 elongated between the buccal mass and nerve ring, forming a long 

 loop. The walls of the oesophageal loop are thick and formed from 

 distinct longitudinal muscle fibres. The buccal sac is not defined. 



Glands 



The salivary glands are large, consisting of single tubes, surrounded 

 by acinous cells (acinous tubular type). The ducts are thick and 

 coiled. The venom gland changes in histology while passing 

 anteriorly through the nerve ring. The duct of the gland is narrow, 

 unciliated and opens into the posterior buccal cavity. The muscular 

 bulb is medium-sized, its wall formed of two layers of circular 

 muscle fibres (the outer layer being nearly three times thicker than 

 the middle, divided by a connective tissue layer, with a third inner- 

 most, thin layer of longitudinal muscle fibres. 



Odontophore and radula 



The odontophore is medium-sized, with paired, unfused cartilages. 

 The radula consists of marginal teeth (Fig. 23d which are paddle- 

 shaped with a broad distal blade and a long narrow shaft. The distal 

 tip is pointed, with knife-like edges on either side and a blunt barb. 

 An inconspicuous, thin, secondary limb lies along the margin of the 

 main shaft of the tooth. 



Remarks 



The unusual feature of this species is that the buccal mass can be 

 protracted way beyond the proboscis tip and out through the 

 rhynchostome (Taylor, 1994, fig. 8). Nevertheless, in the retracted 

 position the buccal mass lies at the proboscis base. It is possible that 

 the presence of the valvule is also connected with the possibility of 

 buccal mass eversion. 



Funa latisinuata (Smith, 1877) 



(Fig. 23c) 



See also Taylor (1994, plate lg, 6b; fig. 10) 



Rhynchodeum and proboscis 



The rhynchodeal sphincter is large. The epithelium of the anterior 

 one third of the rhynchodeum is highly folded and glandular whilst 

 the posterior is composed of a low, inconspicuous, non-glandular 

 and continuous with that of the proboscis wall. 



The proboscis is long, nearly as long as the rhynchodeum and 

 broad with the tip not infolded. The proboscis and buccal tube walls 

 are thin. The mouth is relatively wide. The muscles of the proboscis 

 wall are equally developed along its length. There is a small anterior 

 buccal tube sphincter, but no sac-like enlargement, no epithelial pad 

 and no intermediate sphincter. 



Buccal mass and oesophagus 



The buccal mass is large and situated partially within the proboscis 

 base and uncurved. Its walls are moderately thick and muscular. The 

 oesophagus is greatly elongated between the buccal mass and nerve 

 ring forming a long loop.The walls of the oesophageal loop are thick 

 and muscular. There is no buccal sac. 



Glands 



The salivary glands are large and acinous, but with a modified 

 histology. The ducts are thick and coiled. The venom gland changes 

 in histology while passing anteriorly through the nerve ring. The 

 anterior part has thick muscular walls and opens into the posterior 

 part of the buccal cavity. The muscular bulb is medium-sized, with 

 the wall formed from two equisize layers of circular muscles, 

 divided by a thick connective tissue layer, with a very thin innermost 

 layer of longitudinal muscle fibres. 



Odontophore and radula 



The odontophore is medium-sized, with paired, unfused cartilages. 

 The radula consists of marginal teeth only (Fig. 23c) which are 

 paddle-shaped, with a flattened, angular, barb-less, distal termina- 

 tion, and a long thin shaft. A thin accessory limb lies along the shaft. 



Ptychobela suturalis (Gray, 1838) 

 (Figs 22, 23a, 30c) 



Rhynchodeum and proboscis 



The rhynchodeal sphincter is medium-sized and situated rather to 

 the posterior of the rhynchostome. The epithelium of the anterior 

 one third of the rhynchodeal cavity is folded and formed of tall, 

 glandular cells. The low, non-glandular epithelium of the posterior 

 two thirds of the rhynchodeum is continuous with that of the 

 proboscis wall. This indicates that a large part of the rhynchodeal 

 wall takes part in proboscis protraction. 



In retracted animals, the proboscis is short with the tip infolded 

 (Taylor 1994, fig. 18). However, in relaxed animals, the proboscis is 

 very long, longer that the rhynchocoel and with the tip not inverted. 



