72 COyClWLW—DITHYRA. 23. 



^# Dcntes lateral<'s l/pt^s, 6-10. 

 The lateral teeth smooth. 



Siuitomta. Mactra tesfd frigond diaphand toHvexd €equiJaterali irans- 

 rersiin suhstriatd, latere an tiro rtigoso. 

 Shell triangular transparent convex equilateral slightly striate 

 transversely, rough ou one of the siiles. 

 Mactra Stultorum. Linn. Syst. Nat. p. 1126. 

 Crmelin, Syst. p. ii2o8. 

 Turfon, Linn. S^st. iv. p. 211. 

 Pennant, iv. p. 193, tab. 52, fig. 1. 

 Chemnitz, vj p. 226, tab. 23, tig. 221 to 227. 

 Montagu, Test. Brit. p. 94. 

 Donovan, British Shells, iii. tab. 106. 

 Itinn. Trans, viii. p. 69. 

 TurtoH, Brilish Fauna, p. 154. 

 Dorset Catal. p. 32, tab. 8, fig. 3. 

 DiUwyn, Descript. Catal. p. 138. 

 Tnrton, Conch. Diet. p. 81. 

 Trigonella radiata. Da Costa, p. 195, tab. 12, fig. 3. 

 Mus. nost. Ou most sandy coasts. 



Shell an inch and a half long, and an inch and three-quirters 

 broad, very thin and brittle, white grey or pale brown, covered 

 with a fine wrinkled skin which is rough at one of the ex- 

 tremities, radiate more or less fmm tlie hinge with paler 

 stripes, and sometimes of a purplish cast about the beaks, 

 rarely glossy white and without rays. 



