140 MACTRA. 



solida. 21. Shell sub-triangular, thick, opake, with 

 a few concentrical ridges, and the lateral teeth 

 striated ; hinge central. 



Mactra solida. Linnaus Syst. Nat. p. 1126. Pennant 



Zool. iv. p. 92. t. 51. f. 43. A. Chemnitz, vi. p. 230. 



t. 23. f. 229 and 230. Schroeter Einl. iii. p. 78. Gme- 

 - lin, p. 3259. Donovan, ii. t. 61. Montagu Test. p. 



92. Maton and Racket, in Lin. Trans, viii. p. 70. 



Dorset Cat. p. 32. t. 12 f. 1. 

 Trigonella zonaria. Da Costa Brit. Conch, p. 197. t. 14. 



f. 6. ? 

 Bonanni Rec. 2. f. 51, and Kirch, f. 50. Lister Anim. 



Ang. t. 4. f. 24. Petiver Gaz. t. 94. f. 7. Knorr, vi. 



t. 8. f. 5. 

 Inhabits the European Ocean. Linnaus. Coasts of Britain. 



Lister, fyc. 

 Shell commonly about an inch and a half long, and an inch 

 and three quarters broad ; strong, thick, of a yellowish 

 white colour, becoming grey, or slate coloured, when worn, 

 and marked with a few concentric ridges ; the lateral teeth 

 are large and striated, and the inside glossy white. 



solidissima. 22. Shell ovate, sub-triangular, solid, 

 with obsolete concentral ridges, and the lateral 

 teeth striated ; hinge nearly central. 



Mactra solidissima. Chemnitz, x. p. 360. t. 170. f. 1656. 

 Mactra procera. Solander's MSS. Portland Cat. p. 24. 



lot 559. 

 Mactra solida Var. £. Gmelin, p. 3259. 



Inhabits the coasts of North America. Chemnitz.' Florida, 

 and New Jersey. Solander. New York. Humphreys. 



Shell generally about three inches and a half long, and five 

 inches broad, but sometimes still larger, and remarkably 

 solid, thick, and opake ; it differs from M. solida, not only 

 in its far greater size, but also in being proportionably 

 broader, and more ovate, and in having the hinge placed a 

 little nearer the posterior than the anterior end. 



truncata. 23. Shell triangular, equilateral, strong, 

 with a few concentric ridges, and the urn- 

 bones thick, and prominent; lateral teeth 

 striated. 



