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POPULAR CONCHOLOGT. 



Order II. 

 GYMNOSOMATA. 



The body of the animals of this order are naked, without 

 shell. The head is distinct ; the fins are two, rarely four ; 

 the gills, when present, external. 



As they possess no trace of a shell, the generic names 

 alone will be given. 



Family 1 . — CLIONA CEA. 



Clione Pallas ; Cliodita Quoy and Gaim. ; Pelagia Quoy 

 and Gaim. 



Family 2. — PNE UMODERMA CEA. 



Pneumodermon Cuvier ; Spongiobranchaea U Orb. ; 

 Trichocyclus Esch. 



Family 3.— CYMOD O CEA CEA. 



Cymodocea D'Orb. 



Class IV. — CONCHIFEEA. 



The animals of this class have the body enclosed in a 

 mantle of two lobes (as a book lies between its covers), 

 but on its under side the edges of the lobes are not always 

 free, but often more or less united. This mantle possesses 

 the property of elaborating lime granules on its outer sur- 

 face, which gradually become organised into two shells or 



