54 



GENERtC SYSTEM. 



into the opposite valve, as Mya, Solen, Tellina, 

 Donax ; or inserted, as Cardium, Mactra, Venus, 

 Spondylus, Chama, Area ; and 2dly, those with- 

 out teeth, as Ostrea, Anomia, Mytilus, Pinna. 



Univalves are distinguished into those, 1st, pos- 

 sessing a regular spire, which, as to their aper- 

 ture, are either effuse, as Conus, Cypraea, Bulla, 

 Voluta; canaliculate, as Buccimmi, Strombus, 

 Murex; or coarctate, as Argonauta, Nautihis, 

 Trochus, Turbo, Helix, Nerita, Haliotis : 2dly, 

 having no spire, or a very irregular one, as Patella, 

 Dentalium, Serpula, Teredo, Sabella. 



The Linnaean genera are thirty-six in number, 

 and are thus arranged. 



Multivalves, 



1 Chiton 



2 Lepas 



3 Pholas 

 Bivalves, 



4 Mya 



5 So'len 



6 Tellina 



7 Cardium 



8 Mactra 



9 Donax 



10 Venus 



1 1 Spondylus 



12 Chama 



13 Area 



14 Ostrea 



15 Anomia 



16 Mytilus 



17 Pinna 

 Univalves. 



18 Argonauta 



19 Nautilus 



20 Conus 



2 1 Cvpraea 



22 Bulla 



23 Voluta 



24 Buccinum 



25 Strombus 



26 Murex 



27 Trochus 



28 Turbo 



29 Helix 



30 Nerita 



31 Haliotis 



32 Patella 



33 Dentalium 



34 Serpula 

 33 Teredo 

 36 Sabella. 



