46 



Mactra straminea 



Mactra ovalina 



austral is 



alba 



violacea 



solida 



fasciata 



castanea 



turgida 



rufa 



plicataria 



squalida 



rufescens 



Brasiliana 



maculata 



donacina 



subplicata 



depressa 



triangularis 



lilacea 



lactea 



trigonella 



abbreviata 



deltoides 



Mactra crassatella. 



CRASSATELLA. 



MACTRA STRIATA.— Gmelitl. 



Chemnitz, 6, tab. 22, Jig. 222, 223. 

 A great affinity exists between this genus and those 

 of the Mactra and Lutraria, it having, like them, the 

 ligament of the valves internal, and attached to the 

 primary cavities of each valve, but when closed they 

 fit exactly, and do not gape, as in the above genera.— 

 In some species the ligament is partially visible on the 



