4 SYSTEMATIC INDEX. 



Pages 



37. Physa fontinalis. Stream Bubble-shell, . 49, 112 



14. PLANORBIS. COIL-SHELL, .... 49,113 



38. Planorbis Vortex. Angular-mouthed 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. GASTEROPODAPECTINIBRANCHIATA50, 121 



SECTION I. ASIPHONATA, . 50, 122 



FAMILY I. PALUDININA, , 51,122 



16. PALUDINA. MARSH-SHELL, ... 51, 122 



43. Paludina vivipara. Viviparous Marsh-shell, . 51,123 



17. BYTHINIA. BYTHINIA, . . . 51, 123 



44. Bythinia tentaculata. Tentaculated Bythinia, . 51, 124 



FAMILY II. NATICINA. . 51, 124 



18. NATICA. NATICA, . . . . 61,124 



45. Natica monilifera. Beaded Natica, . . 51, 125, 345 



46. Natica rutila. Ruddy Natica, . . 51, 126 



47. Natica Alderi. Alder's Natica, . . 52, 126 



48. Natica nitida. White Natica, . . 52, 127 



49. Natica helicoides. Helicine Natica, . . 52, 128 



50. Natica squalida. Dull-coloured Natica, 52, 128 



19. NERITINA. NERITINE, .... 52, 129 



51. Neritina fluviatilis. River Neritine, . . 52, 129 



FAMILY III. TURBININA, . 52, 130 



20. TROCHUS. PYRAMID-SHELL, ... 52, 131 



52. Trochus zizyphinus. Zizyphine Pyramid-shell, 53, 131 



53. Trochus conuloides. Conuloid Pyramid-shell, . 53, 132 



54. Trochus millegranus. Granulated Pyramid-shell, > eo i oo o,m 

 Trochus Martini. Martin's Pyramid-shell, \ OJ > 1<w > J4( 



55. Trochus umbilicatus. Umbilicated Pyramid-shell, 53, 132 



56. Trochus cinerarius. Grey Purple-streaked Pyramid-shell, 53,133 



57. Trochus tumidus. Tumid Pyramid-shell, . 53, 133 



21. MONODONTA. MONODONTA, . . 325 



58. Monodonta crassa. Solid Monodonta, 325 



22. PHORCUS. PHORCUS, . . 53, 134 



59. Phorcus Margarita. Pearly Phorcus, . 53, 134 



23. SKENEA. SKENEA, ... 53, 134 



60. Skenea depressa. Brown Skenea, . . 54, 134 



61. Skenea serpuloides. Serpuline Skenea, . 54, 135 



62. Skenea divisa. Semistriated Skenea, . . 54, 135 



24. LITTORINA. PERIWINKLE, . . . 54, 135 



63. Littorina littorea. Common Periwinkle, . 54, 136 



64. Littorina jugosa. Ridged Periwinkle, . . 326 



65. Littorina rudis. Coarse Periwinkle, . . 54, 137 



66. Littorina saxatilis. Rock Periwinkle, . . 54, 138 



67. Littorina tenebrosa. Marsh Periwinkle, . 54, 138 



