109 



PAGE. 



Nerve centres anterior 66 



pallial 71, 72 



pedal 67 



penis 67 



of proboscis and proboscis 



sheath 69 



visceral 73 



endings in osphradium 80, 81 



Nervous system 65 



Nephridium 83 



Nephridial gland 87 



Nephridio-cardiac vein 58, 64 



Odontoblasts 52 



Odontophore 31, 43 



bands 44 



cartilage 45 



histology 50 



muscles 44 



mode of action ... 47 



Oesophagus 31, 38 



caecum 33, 40 



epithelium 39 



Operculum 4, 13 



Optic vesicle 74 



Osphradium 18, 77 



leaflets 78 



nerve endings... 80, 81 



Otocysts 68, 82 



Ovary 93 



Pallial artery 59 



cavity 17 



complex 17 



circulation 64 



nerves 71, 72 



siphon 18 



Parasites 107 



Patella 55, 89 



Pectinibranchia 2 



Pedal ganglia 67 



gland 10, 16 



groove 4, 15 



Penis 90 



nerve 67 



Periostracum 6, 7 



secretion of 9 



Pharynx 30, 35 



Pleural ganglia 69 



Pleurekbolic 30 



Pleurembolic 30 



Proboscis 28 



Prosobranchia 2 



PAGE. 



Radular teeth 49 



variation in teeth 49 



formation and growth 52, 53 



Rectum 35 



glands 35 



Renal aperture 19, 35 



organ 83 



blood supply 63 



principal system... 86 

 secondary lamellae 86 



sinus system 62, 63 



Reno-mucous vessel 57, 62, 64 



Reno-pericardial aperture 84 



Reproductive organs 89 



Rhynchodaeum 30 



Rhynchostome 30 



Salivary ducts 32. 38 



glands 31,' 38 



Sense organs 73 



Shell 4 



formation 9 



layers 7 



sinistral 5 



siphon 6 



sutures 5, 6 



structure 8 



Silica in teeth 55 



Spermatozoa 91 



Stiftchen 76 



Stomach 33, 40 



Streptoneura def 1, 2 



Streptoneurous twisting 65 



Tentacles 3 



supernumerary 3 



Tentacular artery 61 



nerve 68 



Testis 89 



" Triangle lateral " 67 



Vaginal oviduct 93 



Vascular system r 55 



Venous system 61 



Ventricle 58, 59 



Visceral aorta 59, 61 



commissure ... 65, 66, 71 



ganglia 72 



mass 3 



nerves 73 



Whorl 



