74 CO^GRYLIA—DITHYRA. 23. 



Mactra glauca. Gmelin, Syst. p. 3260. 



Turton, Linn. Syst. iv. p. 212. 



Montagu, Test. Brit. p. 571. 



Donovan, British Shells, iv. tab. 12-5. 



Pennant, Brit. Zool. iv. p. 192. 



Linn Trans, viii. p. 68. 



Dillwyn, Descript. Catal. p. 144. 



Turton, Conch. Diet. p. 80. 

 Mactra helva. Chemnitz, vi. p. 234, tab. 23, fig. 232, 233. 



Found by Miss Pocoek on Hale sands, in Cornwall ; from which 

 neighbourhood some single valves have been lately procured by 

 General Bingham. 



Shell nearly two inches and a half long, and three and a half 

 broad, of a pale color marked with faint irregular glaucous rays, 

 flattish and finely striate transversely: the beaks recurved, not 

 quite central, with a narrow gape under them. 



fragilis. Mactea testd ovato-oblongci planiusculd suheBquilaterali Imvi, antice 

 anguloso flexuosd. 

 Shell oval-oblong flattish nearly equilateral and smooth, with an 

 angular flexure at the anterior side. 



Tab. nost. 4, fig. 10. 

 Mactra fragilis. Gmelin, Syst. p. 3261. 



Turton, Linn. Syst. iv. p. 213. 

 Chemnitz, vi. p. 236, tab 24, fig. 235. 

 Mus. nost. Dredged in the Channel, near Guernsea. 



