72 



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



Fig. 18 Radulae of Epidirona and Gemmula (outgroup). a, Epidirona gabensis scale bar = 20pm b. Gemmula deshayesi scale bar = 25pm. 



paired unfused. The radula is composed of marginal teeth. These 

 teeth (Fig. 1 8a) are of the wishbone type with the distal half tapering 

 to a sharp point, whilst the proximal part of the tooth bifurcates into 

 two more or less equisized limbs. The marginal tooth are medium 

 long, ca.l20um (0.5% of SL, 1.8% AL). 



Inquisitor latifasciata (Sowerby, 1 870) 



(Figs 17b, 20) 



See also Taylor (1994, plate le,7; figs 1 1-12) 



Rhynchodeum and proboscis 



The rhynchodeal sphincter is large and anteriorly situated. The 

 epithelium of the anterior two thirds of the rhynchodeal cavity 

 consists of very tall cells, is glandular, and folded. The epithelium of 

 the posterior one third of the rhynchodeum is continuous with that of 

 the proboscis wall, and consists of low, cubic, non-glandular cells. 

 The rhynchostome is narrow. 



The proboscis is long in semi-relaxed animals, and lies coiled 

 within the rhynchodeal cavity. In retracted specimens, the proboscis 

 is very short, less that one third of the rhynchocoel and infolded at 

 the tip. The proboscis wall is not thick in retracted specimens, and 

 comprises about 8% of the proboscis diameter. The mouth is narrow 

 in semi-relaxed animals, but is capable of great stretching and is very 

 wide in retracted specimens (Fig. 20). The muscles of the proboscis 

 wall are equally developed along its length. Both anterior and 

 intermediate buccal tube sphincters are absent and there is no sac- 

 like enlargement of the buccal tube. The buccal tube is very 

 thin-walled in the anterior part (in the inverted position of the 

 proboscis tip), but rather thick posteriorly, where it is nearly equal to 

 the proboscis wall in width. The buccal lips are very large and form 

 the muscular tube, which in retracted specimens extends beyond the 

 mouth of the proboscis. 



Buccal mass and oesophagus 



The buccal mass is muscular, with thick walls and a rather narrow 

 inner cavity which is not curved. In the retracted state, it lies just 

 within the base of the proboscis, but can clearly be protracted to near 

 the distal tip of the proboscis. There are several retractor muscles, 



attached to the buccal mass at one end and to the rhynchodeum at the 

 other. The oesophagus is slightly elongated between the buccal mass 

 and nerve ring, forming a short loop. 



Glands 



The salivary glands are large, paired and acinous. The histology of 

 the venom gland changes abruptly in histology after passing ant- 

 eriorly through the nerve ring. The duct of the gland is narrow and 

 opens just posterior to the buccal cavity. The muscular bulb wall is 

 formed of two equal layers of longitudinal muscle fibres, divided by 

 a connective tissue layer. 



Odontophore and radula 



The odontophore is medium sized, with paired, unfused, 

 odontophoral cartilages. The buccal sac is long. The radular com- 

 prises marginal teeth only, with each tooth of the wishbone type 

 (Fig. 17b) with a large robust major limb with a distal point and a 

 smaller, slender secondary limb 



Inquisitor aemula ( Angas, 1 877) 

 (Figs 17c, 21) 



Rhynchodeum and proboscis 



The rhynchodeal sphincter is medium-sized and anteriorly located. 

 The epithelium of nearly the whole rhynchodeum is glandular and 

 only in a small posterior portion is it low, cubic and non-glandular, 

 like that of the proboscis. 



The proboscis is very long, longer than the rhynchodeal cavity 

 and curved when retracted. The proboscis walls are thin, comprising 

 about 10% of the proboscis diameter. The mouth is very narrow, with 

 a low 'rim'. Muscles of the proboscis wall are equally developed 

 along its length. There is no anterior buccal tube sphincter, but there 

 is a large intermediate sphincter, which lies at a distance of about 

 three marginal tooth lengths from the mouth opening. The sac-like 

 enlargement of the buccal tube has a wide lumen, with the epithe- 

 lium near the mouth opening being columnar and moderately tall, 

 soon becoming low, but forming the epithelial pad, to which a 

 marginal tooth was attached. The buccal tube has moderately thick 



