68 



Y.I. KANTOR, A. MEDINSKAYA AND J.D. TAYLOR 



Fig. 14 Radulae of Crassispirinae a, Hindsiclava militaris b, H. militaris c, 

 20um. 



Miraclathurella bicanalifera (Sowerby, 1 834) 

 (Fig. 14c) 



Rhynchodeum and proboscis 



The rhynchodeal sphincter is small and anteriorly located. The 

 epithelium of the anterior part of the rhynchodeal cavity is glandular, 

 whilst that of the posterior rhynchodeum is low, non-glandular, and 

 continuous with that of the proboscis wall The rhynchostome is 

 rather wide. 



The proboscis is as long as the rhynchodeal cavity, highly folded, 

 and very thick at the base, but sharply narrowing towards the tip. The 

 proboscis walls are thick and form about 22% of the proboscis 

 diameter at its base. The wall muscles at the proboscis tip are much 

 thinner. The proboscis is very muscular and its lumen is mostly filled 

 with the retractors. The mouth is narrow. The anterior buccal tube 

 sphincter is absent. The sac-like enlargement of the buccal tube is 

 poorly defined, but lined with taller epithelium with a small epithe- 



Miraclathurella bicanalifera d, Haedropleura septangularis. Scale bars = 



Hal pad. There is a large intermediate sphincter, situated approxi- 

 mately one third of the distance down the proboscis. The buccal tube 

 is very narrow anteriorly, but broad in the posterior part of the 

 proboscis. Its walls are highly folded and compose about 10% of the 

 proboscis diameter. The buccal tube is lined with a very low epithe- 

 lium, which is replaced with a tall one, continuous with that of the 

 buccal cavity, slightly anterior to the buccal cavity. 



Buccal mass and oesophagus 



The buccal mass is large, slightly less that half of the proboscis 

 length, and lies within the proboscis. It has rather thick walls with no 

 curvature. The buccal lips are very small and poorly defined. Ante- 

 rior to them, the walls of the buccal tube form a fold, similar in 

 appearance to the true buccal lips. The oesophagus is elongated 

 between the buccal mass and nerve ring and forms a medium-long 

 loop. A buccal sac is absent. The salivary ducts open in the buccal 

 cavity on both sides of the very broad opening of the radular 

 diverticulum. 





