52 



ends. Hinge with two distant tubercles, or obsolete 



teeth: ligament exterior. 



Saxicava rugosa Saxicava pholadis 



gallicana australis 



Saxicava veneriformis. 



PETRICOLA. 



VENUS LYTHOPHAGA. GmelilU 



Chem.% MS,/. 15. 

 The shells of this genus are borers, at least such as are 

 known: they are bivalves, transverse, inequilateral ; 

 upper side narrowed and a little gaping; lower side 

 rounded. Hinge with two teeth on each valve, but 

 ometimes with only one. 

 Petricola lamellosa Petricola rocelaria 



ochroleuca exilis 



semilamellata ruperella 



lucinalis chamoides 



striata pholadiformis 



costellata labagella 



Petricola linguatula 



