66 BIVALVES. — OSTREA. 



Family 3 — Rounded at the hinge. 

 Regula — Tongue-shaped. 



Family 4. — Valves diverging at the hinge, and the inside 



vaulted. 



Fornicata — Vaulted. 



Division IV. — Parasytical, or attached to other 



SUBSTANCES. 



Family 1. — With one valve produced at the summit. 

 Cucullata — Hooded. Forskalii — ForskaeVs. 



Virginea — Virginian. Cristata — Crested. 



Rostrata — Beaked. Sinensis — Chinese. 



Family 2.-^With the valves nearly equal. 

 Orientalis — Indian. Orbicularis — Orbicular. 



Folium — Foliated. Arborea — Tree. 



Plicata — Plaited. Senegalensis — Senegal, 



Family 3. — With the valves strongly plaited longitudinally. 

 Crista-galli — Coxcomb. Hyotis — Horned. 



Fi-ons — Crested. 



Division V. — With the hinge composed of transverse 



FURROWS in a straight LINE. 



Crenatula — Crenated. Ephippium — Saddle. 



Semiaurita — Half-eared. Alata — Winged. 



Perna — Oblong. Picta — Painted. 



Isognomon — Long-hinged, Legumen — Pod-shaped. 



Division VI. — Valves slightly striated, lower valve 

 turning up at its sides, and the cartilage of 



THE hinge placed IN A DEEP NARROW GROOVE. 



Spondyloidea — Spondyloid. Ovalis — Oval. 



Divison VII. — Valves coarse and rugged, and not com- 

 prehended IN the former divisions. 



Denticulata — Toothed. *Edulis — Eatable. 



