MYAD^. 



55 



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

 and rarely in stone. 



Panojicea (Menard). Shell equal- valved, oblong, 

 gaping at both ends; hinge-teeth t prominent; 

 ligament external on ridges. Animal with long 

 united siphons, and a short, thick foot. 



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



70 



71 



O 



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. 7] ; n. s. 



Necera (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 w ' 

 short siphons, and a lanceolate foot. 



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

 costellata. 

 abbreviata. 



V 



>b 



\CAi 



'o 



C 



-? 



X 



vc 







