126 SPECIFIC 



on the area well defined ; anterior side nearly 

 flat, posterior one convex except towards the 

 margin. 



Inhabits the Indian ocean. 



PLATE VI. 

 Fio-. 1, TIiNGE of Mactra hitraria. 



Fig. 2. Mactra Stultoriim. 



Shell subdiaphanous, smooth, obsoletely radiate, 

 purplish within ; area gibbous. 



Listei- Conch. Tab. 251. 



Specimen pale brown inclining to cinereous, 

 with paler rays, finely striate transversely. 



Inhabits the English coast. 



Fig. 3. Hinge of DoNAx Scortum. 



Fig. 4. Don AX denticulata. 



Shell very obtuse on the anterior side; lips 

 transversely wrinkled ; margin denticulate ; shell 

 striate longitudinally. 



Lister Couch. Tab. 376. Fig. 218, 219. 



