XXViii. 
DIBRANCHIA. PSEUDOLAMELLIBRANCHIATA. 
Lucinacea. Ostreidee 
Lucinide. Aviculide, 
Tellinacea. Pectinidee 
Tellinidee. Limide. 
Scrobiculariide, FILIBRANCHIATA. 
Anatinacea. Mytilide (ex. Dreissensia). 
Cuspidariide. Anomiide. 
Pandoride. Arcide. 
Lyonsiide. PROTOBRANCHIATA. 
Anatinide. Nuculide. 
The order therefore adopted is :— 
Arcacea. 
Family Arcide. 
Genus Arca, L, 
Barbatia, Gray. 
Peetunculus, Lam. 
Limopsis, Sassi. 
Nuculacea. 
Family Nuculide. 
Genus Nucula, Lum. 
Lada, Schum. 
Ostracea. 
Family Ostieide. 
Genus Ostrea, L. 
Family Anomiidae. 
Genus Anomia, L. 
