136 



J.D. TAYLOR, Y.I. KANTOR AND A.V. SYSOEV 



1mm 



Fig. 14 Funa latisinuata; anterior alimentary system. A, proboscis 

 with buccal mass in extended position; B, with buccal mass in 

 retracted position and showing the loop of the oesophagus 

 situated to the anterior of the nerve ring. Modified from an 

 unpublished drawing by J. Miller. Abbreviations: bm, buccal 

 mass; bt, buccal tube; con, circum-oral nerve ring; mb, muscular 

 bulb; ol, oesophageal loop; vg, venom gland. 



Fig. 15 Diagrammatic section through the radular sac. A, in 

 turrids possessing an odontophore; B, turrids lacking an 

 odontophore, but with a radula caecum. Abbreviations: bs, 

 buccal sac; od, odontophore; rs, radular sac; re, radula caecum; 

 sip, sublingual pouch; t, radular teeth. Buccal sac is that portion 

 of the radular sac lying between the entrance of the salivary ducts 

 and the buccal cavity. 



3. Marginal teeth 



In most conoideans the marginal teeth are the principal 

 functional teeth. Although diverse in appearance, they can be 

 divided into three broad categories of solid, wishbone and 

 hollow. There may be several subdivisions of each category. 

 Teeth of the first category are represented by a single, flat, 

 distally acute plate. Wishbone teeth are characterised by two 

 plates connected to each other. Hollow teeth are distin- 

 guished by a cavity within the tooth. 



a) Solid marginal teeth 



We recognise four main categories of solid teeth, (i) Simple, 

 flat teeth, often with a simple, blunt barb (Figs 16a, f, Fig. 

 20a). This type of tooth is common in the Drilliinae. (ii) 

 Simple teeth as in (i), but with the lateral edges of the tooth 

 curved to form a channel or gutter. This type of tooth has 

 been recorded from Drillia cydia (Powell, 1966, fig 81; Maes, 

 1983, fig. 28). (iii) Simple, solid teeth, which are curved and 

 pointed (Fig. 17e). This type of tooth is found only in 

 Pseudomelatominae (Kantor, 1988) and the Pervicaciidae 

 (Taylor, 1990). (iv) Simple, awl-shaped teeth with a large base 

 and pointed tip and a spathulate process midway along the 

 tooth (Figs 17a-d). This type of tooth has been found only in 

 the subfamily Strictispirinae. 



b) Wishbone teeth (sometimes called duplex teeth) 



In this type of dentition, the marginal teeth consist of two 

 parts, comprising the main tooth together with an accessory 

 limb. Published illustrations suggest a great variety of form in 

 wishbone teeth, but S.E.M. observations show that some of 

 this variety results from artifacts produced by the transpar- 

 ency of light microscopy and by different positions of teeth 

 (often with displaced tooth parts) in preparations. 

 We recognise four basic types of wishbone teeth: 

 (i) Broad, slightly curved teeth, sometimes with a blunt 

 barb (Fig. 20 b-d). The lateral edges of the teeth are 

 thickened, with a thin accessory limb attached to the main 

 tooth at the anterior and posterior ends. This type of tooth is 

 common in some Crassispirinae such as Inquisitor, Paradrillia 

 and Funa, where the size and shape of the accessory limb 

 varies considerably between species (Kilburn, 1988). Because 

 the main limb is similar to the marginal teeth of the Drillii- 

 nae, we suggest this as the least-derived type of wishbone 

 tooth, (ii) The teeth of this type are robust, short and curved, 

 sometimes with a knife-like cutting edge on the main limb 

 and a large accessory limb (Figs 18a,c; 19a, d). Teeth of this 

 type are found in species of Turrinae, Clavatulinae, and 

 Cochlespirinae. (iii) Teeth that may be modified wishbone 

 teeth have been illustrated for Ptychobela nodulosa and 

 P.suturalis by Kilburn (1989, figs 17-19). The teeth are 

 awl-shaped without barbs, with apparently two nearly equi- 

 size limbs joined to form a central channel. An S.E.M. study 

 of these teeth is needed to claify their morphology, (iv) In the 

 radula of Ptychobela griffithi the teeth appear to be robust 

 and solid with a simple barb (Fig. 22a), but they may in fact 



Fig. 16 Radulae of Drilliinae. a, half radula row of Clavus sp. from Guam showing blade-like marginal teeth, comb-like lateral teeth and the 

 small central tooth. Scale bar = 50 um. b, central tooth of Clavus unizonalis. Scale bar = 5 um. c, central and part of lateral teeth of 

 Spirotropis monterosatoi . Scale bar = 20 um. d, central tooth of S. monterosatoi. Scale bar = lOum. e, single lateral tooth of S. 

 monterosatoi. Scale bar = 20 um. f, marginal teeth of S. monterosatoi. Scale bar = 20 urn. 



Fig. 17 Radulae of Strictispirinae and Pseudomelatominae. a, radula of Strictispira paxillus. Scale bar = 50 um. b, marginal teeth of 

 Strictispira stillmani. Scale bar = 50 urn. c, radula of Cleospira ochsneri. Scale bar = 50 um. d, marginal teeth of Strictispira paxillus seen 

 from side. Scale bar = 50 um. e, radula of Pseudomelatoma penicillata. Scale bar = 100 um. f, central tooth of P. penicillata seen from side. 

 Scale bar = 10 um. (see p. 138) 



