68 



CONCHIFERA. 



ligament external, prominent ; pallial line slightly 

 sinuated ; muscular impressions square. Animal 

 with mantle open in front ; siphons two, very 

 short, thick, fringed ; foot large, hooked. 



Cardium (Linn.). Cockle. Sliell swollen ; beaks 

 nearly central, prominent, margins indented ; teeth 



1^1 



T 2? 1* 



C. aculeatum. 



echinatiim. Fig 106 ; | 



rusticum. 



eclule. 



fasciatum. 



C nodosum. 

 n. s. Norvegicum. 



jDygmseum. 

 Suecicum. 



107 



106 



Teibe II. Asiphonida. 



Hinge composed of many teeth . Arcade. 

 Hinge nearly or quite toothless. 

 Two miiscularimpressions : 



Covered w^th dense epidermis . 

 Without epidermis .... 



One muscular impression 



MytilidiT.. 

 Aviculadcp. 



Ostreadce, 



