HELIX 



8. Nerve-collar and chief nerves shown by drawing the oesophagus forward through the collar, and 

 cutting it in front of the collar, then turning the buccal mass upwards and forwards so as to expose 

 its ventral surface. Cerebral or supra-cesophageal ganglion, giving off a pair of nerves to the buccal 

 ganglia on the dorsal surface of the buccal mass but ventral to the oesophagus ; nerves from cerebral 

 ganglion to the tentacles ; infra-eesophageal ganglion (pedal, pleural and visceral fused) ; nerves from 

 pedal ganglion to foot. 



9. Calcareous spicule removed from the dart-sac and enlarged three times. 



10. Section of hermaphrodite gland, examined under high power. Ova; sperm mother-cells; 

 spermatozoa. 



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64 



