FOREGUT ANATOMY OF CRASSISPIRINE GASTROPODS 



67 



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Fig. 13 Hindsiclava andromeda (Dall, 1919). A, Semidiagrammatic longitudinal section of the foregut (salivary ducts not shown); B. longitudinal section 

 of the proboscis and buccal mass (only one salivary duct is shown). 



proboscis. It has rather muscular walls and is not curved. The buccal 

 lips are asymmetrical, the ventral lip being large, and the dorsal 

 medium-sized. The oesophagus is greatly elongated between the 

 buccal mass and nerve ring and forms a long loop. The opening of 

 the radular diverticulum into the buccal cavity is narrow, and the 

 salivary ducts open at the entrance of radular diverticulum into the 

 buccal mass. A buccal sac is absent. 



Glands 



The salivary glands are very large with the ramified tubular mor- 

 phology. The salivary ducts are very long and thick, but only slightly 

 coiled. The histology of the venom gland changes abruptly soon 

 after passing anteriorly through the nerve ring. The duct of the 

 venom gland is narrow, coiled and unciliated. The muscular bulb is 

 large, with a narrow lumen and thick walls mainly formed of two 

 equal layers of longitudinal muscle fibres, divided by a connective 

 tissue layer, with a thin, innermost layer of circular fibres. 



Odontophore and radula 



The odontophore is small, consisting of a pair of unfused, subradular 

 cartilages, formed by a single layer of cells. Unfortunately, no 

 radular information is available for this species, but it is presumed to 

 be similar to Hindsiclava militaris (see below). 



Hindsiclava militaris (Reeve, 1843) 



(Figs 14a-b) 



Two specimens were sectioned. The species is very similar in 

 general foregut anatomy to H. andromeda and differs mainly in the 

 slightly longer proboscis (which occupies from 1/7 to 1/5 of the 

 rhynchodeum). The proboscis is very muscular, with the entire 

 lumen filled with retractor muscles. The anterior buccal tube sphinc- 

 ter is very small, and hardly visible. The proboscis tip is invaginated. 

 This is confirmed by the change of the epithelium in the anterior part 

 of the buccal tube. A short buccal sac is present. 



Radula 



The radula consists mainly of two rows of marginal teeth. These are 

 wishbone in form but have a very distinctive, hairpin-like morphol- 

 ogy (Figs 14 a-b). The major limb is elongate and pointed, slightly 

 concave-upwards in profile with raised edges. The secondary limb is 

 long and slender, attached to the major limb near the tip but detached 

 and distantly separated for most of the length, with separate attach- 

 ment to the radular membrane. Another feature of the radula is the 

 regular low, transverse ridges which cross the central part of the 

 ribbon (Fig. 14a) The marginal teeth are medium long, ca. 140pm 

 (0.5%ofSL, 1.9% AL). 



