CONCHIFEEA. 



Order II. INTEGROPALLIALIA. 



Furnished with siphons 

 Without siphons . . 



Siphonida. 



Asiphonida. 



TEIBE I. SIPHONIDA. 



Shell without ribs. 



Ligament external, conspicuous ; foot 

 thick, tongue-shaped 



Ligament internal or obsolete ; foot 

 long, cylindrical, or strap-shaped . 



Shell marked with radiating ribs Cardiada. 



FAMILY I. CYPRINAD.E. 



Shell regular, thick, solid, smooth, or marked 

 with concentric lines, usually covered with a thick 

 epidermis ; ligament external, conspicuous ; pallial 

 line simple. Animal with the mantle-leaves united 

 behind by a curtain, pierced with two siphonal 

 orifices ; foot thick, tongue-shaped. 



Isocardia (Lamk.). Heart-shell. Shell heart- 

 shaped, inflated; beaks distant, spirally rolled; 

 teeth T? i? K Animal with siphons close together, 

 short, fringed ; foot pointed. 



I. cor. Fig. 95 ; J n.s. 



