MYAD^E. 55 



gills two on each side. Burrowers in mud, sand, 

 and rarely in stone. 



Panop&a (Menard). Shell equal-valved, oblong, 

 gaping at both ends ; hinge-teeth J prominent ; 

 ligament external on ridges. Animal with long 

 united siphons, and a short, thick foot. 

 P. Norvegica. Fig. 70 ; j- n. s. 



72 



Poromya (Forbes). Shell ovate or roundish, 

 equal-valved, unequal-sided ; surface punctated, 

 covered with a rough epidermis ; hinge a minute 

 erect cardinal tooth in one valve, and a pit in the 

 other. Animal with short siphons, surrounded by 

 tentacles at their base ; foot long, slender. 

 P. granulata. Fig. 71 ; n.s. 



Ne&ra (Gray). Shell pear-shaped, globose, un- 

 equal-valved, smooth ; hinge an oblique spoon-like 

 piece in each valve, with sometimes a minute 

 tooth beside it, and a lateral tooth. Animal with 

 short siphons, and a lanceolate foot. 



N. cuspidata. Fig. 72 ; n.s. 

 costellata. 

 abbreviata. 



