Shells of Common Occurrence. 



153 



75-76. 77-78. 



65-66. Planorbis corneus (the Horny Coil Shell), Linnceus. 

 67. P. albus (the White Coil Shell), Midler. 68. P. 

 nautileus (the Nautilus Coil Shell), Linnceus. 69. P. 

 marginatus (the Margined Coil Shell), Drapamaud. 70. 

 P. carinatus (the Carinated Coil Shell), Muller. 71-72. 

 P. vortex (the Whorl Coil Shell), Linnceus. 73-74. P. 

 spirorbis (the Rolled Coil Shell), Muller. 75-76. P. con- 

 tortus (the Twisted Coil Shell), Linnceus. 77-78. P 

 nitidus (the Fountain Coil Shell), ibid. 



