Fio 74 



Radulae of varipus glossophorpus Mollusca. A, diagram showing mouth, oesophagus, and 

 lingual apparatus of a Gastropod in median sagittal section, a.l, lower lip ; a.u, upper lip ; b, 

 jaw of the left side ; c, outer surface of the snout ; d, oesophagus ; e, fold in the wall of the 

 oesophagus behind the radular sac (71) ; /, anterior termination of the radula and its bed, the 

 point at which it wears away ; g, base of the radular sac or recess of the pharynx ; h, cartila- 

 ginous piece developed in the floor of the pharynx beneath the radula, and serving for the 

 attachment of numerous muscles, and for the support of the radula; i, anterior muscles ; fc, 

 posterior muscles attached to the cartilage ; I, muscle acting as a retractor of the buccal mass ; 

 m, muscle attached to the lower lip ; n, posterior extremity of the radular sacj o, the bed of 

 the radula or layer of cells by which its lower surface is formed ; p, the raflula or lingual 

 ribbon ; q, opening of the radular sac into the pharynx or buccal cavity ; r, cells at the extreme 

 end of the inner surface of the radular sac which produce, as a cuticular secretion, the rows of 

 teeth of the upper surface of the radula. 



B, radula or lingual ribbon of Paiudina vivipara, stripped from its bed. 



C, a single row of teeth from the radula of Trochu* dnerarius (Rhipidoglossate) ; formula : 

 00.5.1.6.00. 



D, a single row of teeth from the radula of lanthina fragilis (Stenoglossate) ; formula : 

 oo.O.oo. 



E, a single row of teeth from the radula of Trachydtrmon cinereum (Amphineura) ; formula : 

 3.1.2.1.1.1.1.1.2.1.3. 



F t a single row of teeth from the radula of Patella vulgata (Docoglossate) ; formula : 



G, a single row of teeth from the radula of Cypraea helvola (Taenioglossate) ; formula : 



' H, a 'single row of teeth from the radula of Nassa annulata (Rachiglossate) ; formula : 

 1.1.1. The common Whelk is similar to this. 



90 



