44 BIVALVES. — CARDIUM. 



CARDIUM— CocA-/e or Heart-shell. 

 Division I. — Heart-shaped, valves compressed, um- 



BONES alternating. 



Cardissa — Venus' s heart. 'Ros^nm:— Smooth edged. 



Humanum — Coricave. Monstrosum — Recurved. 



Division II. — sub-cordate, longitudinally ribbed. 



Family 1. — Having a crescent shaped cavity beneath the 



umhones. 



Retusum — Diana's. 



Family 2. — Ribs armed ivith nodules, elevated rough stria, 



wrinkles, or scales. 

 *Edule — Common. Regulare — Regular. 



Unedo — Strawberry. Glaucum — Glaucous. 



Fragum — White strawberry. *Fasciatum — Banded. 

 Hemicardium — Heart-shaped. *Elongatuin — Lengthened. 

 Tuberculatum — Tuberculated. Leucostomum— White-mouth'' d. 

 Isocardia — Rasp. Magnum — Yellow ribbed. 



Pectiniforme — Pecten. Rigidum — Rigid. 



Maculatum — Spotted. 



Family 3. — With ribs armed, more or less spined. 

 Flavum — Yellow. Rugatum — Gaper. 



Spinosum — Spined. Latum — Broad. 



♦Echinatum — Rake. Ciliatum — Ciliated. 



Lima — Asiatic. * Aculeatum — Spinous. 



Muricatum — Prickly. *Muricatulum — Minute. 



Family 4. — With ribs unarmed. 

 Costatum — Pipe-ridged. Oblongum — Oblong. 



♦Medium — Marbled. Papyraceum — Paper. 



Donaciforme — Triangular, Fimbriatum — Furbelowed. 



*Exiguum — Pigmy. Rusticum — Banded. 



Ringens — Toothed. Islandicum — Iceland. 



*Parvum — Diminutive, 



