80 MACTRA. 



angular, and a small cavity each side ; the lateral 

 teeth remote^ and locking into the opposite valves. 



1. Mactra dealbata. Pellucid Mactra. 



Montagu, pi. 5. f. 1 Linn. Trans, vm. pi. 1. f. 10 Dor- 

 set Cat. pi. 7. f. 7. 



Shell oval, thin, brittle, transparent, white, very finely 

 striate transversely, with a few coarser wrinkles, gaping 

 and very slightly produced at the smaller end, but well 

 vounded at both ; within glossy-white, a little concave, with 

 a plain sharp margin : beaks a little oblique, not quite cen- 

 tral ; the middle tooth in one valve broad, forked, angular 

 close to the beak : length an inch and a half j breadth nearly 

 two. 



At the mouths of rivers : rare. v. m. 



2. Mactra glauca. Glaucous Mactra. 

 Donovan, pi. 125. 



Sbell oval, dirty white, thin, semi transparent, finely 

 striate transversely and wrinkled at the anterior end, mark- 

 ed with broad and narrow longitudinal glaucous IT : 

 beaks reflecting backwards, with a narrow gape between 

 them : length nearly two inches and a half ; breadth three 

 and a half. 



Found by Miss Pocock, in Cornwall : very rare. 



3. Mactra radiata. Radiated Mactra. 

 Donovan, pi. 161. 



Cardium edentulum. Montagu, Suppl p. 29. 



Shell thin, brittle, somewhat triangular and produced at 

 0ns end, ash-color, paler and with a light flesh-color tinge 

 beneath the skin, very faintly and obscurely striate longi- 

 tudinally, with a few broad faint distant transverse wrinkles, 

 and marked with numerous equidistant narrow pale testa- 

 ceous longitudinal rays ; inside smooth, white, with a plain 

 margin, the outer striae being visible in the thin part : beaks 

 pointed, nearly central ; turning a little to one side ; pri- 

 mary teeth none, but immediately under the beaks is a 

 small depression, with the rudiment of a small denticle, and 

 a little remote on each side is a small laminar tooth : length 

 two inches and a half; breadth three inches. 



Found by. Captain Laskey, at Portsmouth : very rare. 



4. Mactra 



