FOREGUT ANATOMY OF CRASSISPIRINE GASTROPODS 



71 



Fig. 17 Radulae of Crassispirinae. a, Nqunw scalpta scale bar : 

 d. Inquisitor aff. adenicus scale bar = 20 pm. 



20pm b. Inquisitor lalifasciata scale bar = 25 pm c. Inquisitor aemula scale bar = 20 pm 



large cells. In approximately the posterior one tenth of the 

 rhynchodeum the epithelium is non-glandular and continuous with 

 that of the proboscis wall. 



The proboscis is short in comparison with the rhynchocoel (about 

 1/5 of its length), rather thick and not coiled. The proboscis walls are 

 thick, forming about 25% of the proboscis diameter. The mouth is 

 very narrow. The muscle of the proboscis walls are equally devel- 

 oped along its length. The anterior buccal tube sphincter is very 

 small and lies posterior to the mouth in front of medium-sized sac- 

 like enlargement of the buccal tube. The epithelium, lining the 

 enlargement forms a large pad, to which the base of a marginal tooth 

 was attached. There is a large intermediate sphincter, situated at 

 about three marginal tooth lengths distant from the mouth opening. 

 The buccal tube has rather thin walls, forming about 10% of the 

 proboscis diameter. It is lined with a tall folded epithelium. 



Buccal mass and oesophagus 



The buccal mass is large in comparison with the proboscis, equiva- 



lent to about two thirds of its length. It lies posterior to the proboscis, 

 with a wide lumen and relatively thin walls. Buccal lips are absent. 

 The oesophagus is greatly elongated between the buccal mass and 

 nerve ring, forming a long loop. Anteriorly, it is wide and flattened, 

 but soon becomes very narrow. There is no buccal sac. 



Glands 



The salivary glands are large, acinous and fused. The venom gland 

 changes in histology abruptly after passing anteriorly through the 

 nerve ring. The duct is very narrow, unciliated, and opens into the 

 buccal cavity at the posterior border with the oesophagus. The 

 muscular bulb is medium sized, of an irregular oval shape, with its 

 wall consisting of a thick outer layer of circular muscle fibres, a 

 connective tissue layer, a thinner layer of circular fibres and a thin 

 innermost layer of longitudinal fibres. 



Odontophore and radula 



The odontophore is medium-sized, with the odontophoral cartilages 



