ALLL TZN SSS 
2S ELLOI 
Dy) 
Fic 74 
Radulae of various glossophorous Mollusea. 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 ; ce, outer surface of the snout; d, oesophagus; e, fold in the wall of the 
oesophagus behind the radular sac (7); f, 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 ; k, 
posterior muscles attached to the cartilage ; 7, muscle acting asa retractor of the buccal mass ; 
m, muscle attached to the lower lip; n, posterior extremity of the radular sac; 0, the bed of 
the radula or layer of cells by which its lower surface is formed ; p, the radula or lingual 
ribbon ; q, opening of the radular sac into the pharynx or buccal cavity ; 7, cells at the extreme 
end of the inner surface of the radular sae which produce, as a cuticular secretion, the rows of 
teeth of the upper surface of the radula. 
B, radula or lingual ribbon of Paludina vivipara, stripped from its bed. 
C,a single row of teeth from the radula of Trochus cinerarius (Rhipidoglossate); formula : 
0.5.1.5. o. , 
D, a single row of teeth from the radula of Janthina fragilis (Rtenoglossate) ; formula : 
0.0.0. t 
E, a single row of teeth from the radula of Trachydermon cinereum (Amphineura) ; formula : 
BU) Ma a a I Ue 
F, a single row of teeth from the radula of Patella vulgata (Docoglossate); formula : 
3.1.2.0.2.1.3. 
G,a single row of teeth from the radula of Cypraca helvola (Taenioglossate); formula: 
ZeleMelez 
H, a single row of teeth from the radula of Nussa annulate (Rachiglossate); formula: 
1.1.1. The common Whelk is similar to this. 
90 
