1 26 SPECIFIC 



on the area well defined; anterior side nearly flat, 

 posterior one convex except towards the margin. 

 Inhabits the Indian Ocean. 



PLATE VI. 

 Fig. 1. Hinge of Mactra lutraria. 



Fig. 2. Mactra StuUorum. 



Shell subdiaphanous, smooth, obsoletely radiate, 

 purplish within ; area gibbous. 



Lister Concli. tab. 251. 



Specimen pale brown inclining to cinereous, with 

 paler ravs, finely striate transversely. 



Inhabits the English coast. 



Fig. 3. Hinge of Donax Scorium, 



Fig. 4. Donax denticulata. 



Shell very obtuse on the anterior side; lips trans- 

 versely wrinkled; margin denticulate; shell striate 

 longitudinally. 



Lhter Cnnck. tab. 3/6. fig. 2 IS, 219. 



Specimen white with obsolete purple rays; area 



