LAMARCK. 



525 



* 



*■* 



2. Shell univalve unilocular 

 spiral sheathing the ani- 

 mal. 



Aperture emarginate, or channelled at its base. Gen. 

 Conus, Cypraea, Ovula, Terebellum, Oliva, An- 

 cillaria, Voluta, Mitra, Colmnbella, Marginalia 

 Cancellaria, Nassa, Purpura, Buccinum, Eburna 

 Terebra, Dolium, Harpa, Cassis, Stronibus, Ptero 

 cera, Rostellaria, Murex, Fusus, Pyrula, Fascio- 

 laria, Turbinella,Pleurotoma, Clavatula, Cerithium 

 Aperture entire and without a canal at its base 

 Gen. : Trochus, Solarium, Turbo, Monodonta 

 Cyclostoma, Scalaria, Pupa, Turritella, Ianthina 

 Bulla, Bulimus, Agathina, Limnaea, Melania, Pyra- 

 midella, Auricula, Valvata, Ampullaria, Planorbis 

 Helix, Helicina, Nerita, Natica, Testacella, Sto- 

 matia, Haliotis, Vermicularia, Siliquaria, Aspergil- 

 lum, Carinaria, Argonauta. 



/ Gen. : Nautilus, Orbulites 

 Shell univalve multilocu- Ammonites, Planulites, 

 lar sheathing or enclo-i Nummulites, Spirula, Tur- 

 sing the animal. rulites, Baculites, Orthocera 



vHippurites, Belemnites. 



II. Acephalous Mollusca. 



Naked, 

 conchiferous. 



1. Shell equivalve with or 

 without accessary pieces. 



2. Shell inequivalve of two' 

 or more valves, of which 

 the principal are un- 

 equal. 

 * Principal valve tubular. 



Gen. : Ascidia, Biphores, 

 Mammaria. 



Gen. : Pinna, Mytilus, Mo- 

 diola, Anodonta, Unio, Nu- 

 cula, Pectunculus, Area, 

 Cucullaea, Trigonia, Tridac- 

 na, Hippopus, Cardita, Iso- 

 cardia, Cardium, Crassatella, 

 Paphia, Lutraria, Mactra, 

 Petricola, Donax, Meretrix, 

 Venus, Venericardia, Cyclas, 

 Lucina, Tellina, Capsa, San- 

 guinolaria, Solen, Glycime- 

 risj Mya, Pholas. 



Gen. : Teredo, Fistulana. 



