PLATE III 



i. Diagrammatic sketch of a foliate gill (Aspidobranch.) 



2. Diagrammatic sketch of a pectinate gill (Pectinibranch). 



3. Diagrammatic sketch of the nervous system of Mollusca : e.g., 

 cephalic ganglion • pl.g., pleural ganglion ; p.g., pedal ganglion ; 0., 

 otocyst ; v. I., visceral loop ; v.g., visceral ganglion. 



4. a, b. Mandibles of Polypus tuberculatus, Blainv. : a, under ; b, upper. 



5. Mandible of Helix nemoralis, Linn. 



6. Mandible of Limax. 



7. Mandible of Limnaa stagnalis, Linn. 



8. One of the buccal plates of Cymatium olearium, Linn, (after a sketch 

 by Wilton). 



9. Side-view of the gizzard of Scaphander lignarius, Linn. The part 

 nearest the head of the animal is upwards. 



10. Front-view of the same, the plates in contact. (Both 9 and 10 

 from drawings by S. P. Woodward.) 



11. Two transverse rows of the radula of Cryptopl'ax (Wilton). 



12. Two transverse rows of the radula of Patella vulgata, Linn, 

 (after Wilton). The whole radula is a long narrow ribbon, sometimes 

 as much as 3 inches in length. 



13. One half of a single row of the teeth in the radula of Gibbula 

 cineraria, Linn, (after Loven). Rhipidoglossa ; formula: oc-i^-i^-i-cx. 



14. Part of a single row of teeth from the radula of Epitonium 

 Tiirtonis, Risso (after Loven). Ptenoglossa ; formula: cc-o-co. 



15. One row of teeth from the radula of Natica monilifera. Lamk. 

 (after Wilton). Taenioglossa ; formula: 2-1-1-1-2. 



16. Radula of Buccinum undatum, Linn, (after drawing by S. P. 

 Woodward) : a., anterior end; /., posterior end. 



17. One row of teeth of the same: /., lateral; ;'., rhachidian. 

 Rhachiglossa ; formula: 1-1-1. 



18. Two teeth from the radula of Voluta (Wilton). Rhachiglossa, in 

 which the lateral teeth are wanting. 



19. a, b. Two views of a tooth from the radula of Conus (after Loven). 

 Toxoglossa; formula: 1-0-1. a Shows the poison duct down the inner 

 side. 



20. Portion of radula of a Cephalopod, Sepiola atlantica, d'Orb. 

 (original by S. P. Woodward). 



21. Portion of radula of Helix pomatia, Linn, (the Roman Snail). 



22. Radula of Helix spread out to show the contrast in form to 

 that of Buccinum, Fig. 16, above. 



Figs. 1 to 8 drazvn by Miss G. M. Woodward. 



