290 



MOLLUSCA 



[CH. 



a little blind pouch, called the radula sac : here is its growing- 

 point, where new teeth are continually being formed as the old ones 

 wear away. In the Limpet (Patella), this radula sac is extra- 



FIG. 131. 



Helix pomatia, opened and the viscera exposed. 

 From Hatschek and Cori. 



Pharynx. 2. Oesophagus. 3. Salivary glands, with duct. 



4. Stomach. 5. Liver. 6. Kectum. 7. Anus. 8. Kidney. 

 9. Inflated commencement of ureter. 10. Opening of ureter to exterior. 

 11. Ventricle. 12. Auricle. 13. Pulmonary vein. 14. Opening 

 of kidney into pericardium. 15. Ovo-testis. 16. Common duct 



of ovo-testis. 17. Albumen gland. 18. Female duct. 19. Male 

 duct. 20. Spermatheca. 21. Flagellum. 22. Accessory glands. 

 23. Penis. 24. Dart sac. 26. Vagina. 26. Eye tentacle, 



retracted. 27. Anterior tentacle, retracted. 28. Muscles which 



retract the head, pharynx, tentacle, etc. 



