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 Forskael's. 



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. 



Frons Crested. 



DIVISION V. WITH THE HINGE COMPOSED OF TRANSVERSE 



FURROWS IN A STRAIGHT LINE. 



Crenatula Crenated. Ephippium Saddle. 



Semiaurita Half -eared. Alata Winged. 



Pern a 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. 



