MACTRA. 141 



Mactra truncata. Montagu Test. Supp. p. 34. 



Mactra subtruncata. Donovan, iv. t. 126. 



Trigonella gallina. Da Costa Brit. Conch, p. 199. t. 15. 



f. 1.? 

 Venus rugata. Gmelin, p. 3289- 



Bonanni Rec. 2. f. 54. and Kirch, f. 52. Lister Conch. 

 t. 253. f. 87. Klein Ost. t. 10. f. 42. 



Inhabits the coasts of Britain. Lister, fyc. 



Shell about sixteen lines long, and eighteen broad, and differs 

 from M. solida, in being more triangular, and in having both 

 the slopes more flattened, the valves deeper, and the urn- 

 bones larger, and more prominent ; the external appearance 

 also is smoother, and the transverse ridges less numerous, 

 and less strongly marked. 



subtruncata. 24. Shell triangular, thickish, fine- 

 ly striated transversely, and the umbones 

 thick, and prominent. 



Mactra subtruncata. Montagu Test. p. 93, and Supp. p. 



37. t. 27. f. 1. Maton and Racket, in Lin. Trans, viii. 



p. 71. t. 1. f. 11. Dorset Cat. p; 32. t. 5. f. 10. 

 Mactra stultorum. Pennant Brit. Zool. iv. p. 92. t. 52. 



f. 42. 

 Trigonella subtruncata. Da Costa Brit. Conch, p. 198. 

 Inhabits the coasts of Britain. Pennant, fyc. 

 Shell about seven or eight lines long, and nine or ten broad, 

 and in form resembles M. truncata, from which it may 

 readily be distinguished by its invariably smaller size, and 

 regular transverse striae. 



australis. 25. Shell transversely oval, and wrin- 

 kled, compressed, nearly equilateral, and 

 rounded at both ends ; hinge with two lateral 

 teeth. 



Mya australis. Gmelin, p. 3321. 



Mya Novas Zealandias. Chemnitz, vi. p. 30. t. 3. f. 19 and 



20. 

 Mya, No. 6. Schroeter Einl. iii. p. 616. 



Inhabits the coasts of New Zealand. Chemnitz. 



Shell about aft inch and a quarter long, and nearly two inches 

 broad, of a dull ochre colour ; Chemnitz doubted the pro- 

 priety of arranging this species with the Myae, and as the 

 valves are said to be closed, it stands better in the present 

 genus. 



