64 



CONCHIFEEA. 



Order 11. INTEGROPALLIALIA, 



Furnished with sij)hons .... Siphonida. 

 Without siphons Asiphonida. 



Tribe I. Siphonida. 



Shell without ribs. 



Ligament external, conspicuous ; foot 



thick, tongue-shaped Cyprhiadce. 



Ligament internal or obsolete ; foot 



long, cylindrical, or strap-shaped . Lucinada. 



Shell marked with radiating ribs Cardiadce. 



95 



96 



Family I. Cyprinad^. 



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-sJiell. Shell heart- 

 shaped, inflated ; beaks distant, spirally rolled ; 

 teeth i, t, }. Animal with siphons close together, 

 short, fringed ; foot pointed. 



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



