SYSTEMATIC INDEX. 



Pages 



37. Physafontinalis. Sti-eam Butble-sheU, . 49,112 



14. Planokbis. Coil-Shell, .... 49,113 



38. Planorbis Vortex. Anfmlar-moiithed Flat Coil-shell, 49, 114 



A. P. Vortex crassulus. Thickish, . 50, 116 



B. P. Vortex spirorbis. Round-edged, . 50, 117 



39. Planorbis contortus. Contorted Coil-shell, . 50,118 



40. Planorbis albus. Bristly Coil-shell, . . 50, 119 



41. Planorbis imbricatus. Crested Coil-shell, . 50, 120 



15. Ancylus. Lid-Shell, .... 50, 120 



42. Ancylus fluviatilis. Oval Lid-shell, . . 50, 121 



ORDERII. GASTEROPODA PECTINIBRANCHIATA 50, 121 



ASIPHONATA, 

 PALUDIXINA, 



SECTION I. 

 FAMILY I. 



16. Paludixa. Marsh-Shell, 



43. Paludina vivipara. Viviparous Marsh-shell, 



17. Btthinia. Bythixia, 



44. Bythinia tentaculata. Tentaculated Bythinia, 



FAMILY II. NATICINA. 



18. N.\TICA. Nattca, .... 



45. Natica monilifera. Beaded Natica, 



46. Natica rutila. Ruddy Natica, 



47. Natica Alderi. Alder's Natica, 



48. Natica nitida. White Natica, 



49. Natica helicoides. Helicine Natica, 



50. Natica squalida. Dull-coloured Natica, 



19. Neritina. Neritine, 



51. NeritinafluAdatilis. River Neritine, 



FAMILY III. TURBININA, 



20. Trochus. Pyramid-Shell, 



52. Trochus zizyphinus. Zizyj>hine Pyramid-shell, 



53. Trochus comUoides. Conuloid Pyramid-shell, 



54. Trochus mUlegranus. Granulated Pyi-amid-shell, 

 Trochus Martini. Martin's Pyraraid-sheU, 



55. Trochus umbilicatus. Umbilicated Pyramid-shell 



56. Trochus cinerarius. GreyPui-ple-strea'kedPyrami 



57. Trochus tumidus. Tumid Pyi-amid-shell. 



21. MONODONTA. MoNODONTA, 



58. Monodonta crassa. Solid Monodonta, 



22. Phorcus. Phorcus, 



59. Phorcus Margarita. Peaily Phorcus, 



23. Skenea. Skenea, 



60. Skenea depressa. Brown Skenea, 



61. Skenea serpuloides. Sei-puline Skenea, 



62. Skenea divisa. Semistiiated Skenea, 



24. Littorina. Periwinkle, . 



63. Littorina littorea. Common Periwinkle; 



64. Littorinajugosa. Ridged Periwinkle, . 



65. Littorina rutlis. Coarse Periwinkle, 



66. Littorina saxatilis. Rock Periwinkle 



67. Littorina tenebrosa. Marsh Periwinkle, 



51, 



50, 122 

 51,122 



61. 122 



51. 123 

 51, 123 

 51,124 



51, 124 

 61,124 



125, 345 

 51, 126 



52. 126 



62. 127 

 52,128 

 52,128 

 52, 129 

 52, 129 



52, 130 

 52, 131 



63. 131 



53. 132 



132, 340 



63. 132 

 d-shell, 53, 133 



53. 133 



325 



325 



53,134 



53, 134 



53, 134 



54, 134 

 54,135 

 54,135 

 54,135 

 54, 136 



326 

 54, 137 

 54, 1.38 

 54,138 



53, 



