GINGLYMACONCHA. MACTRAD&. 285 
Colour testaceous or dirty white; inside white. Length 
nine-eighths ; height seven-eighths of an inch. 
Mactra Stultorum, Penn. Brit. Zool. iv. 92. t. lu. f. 42. 
Mactra subtruncata, Mont. Test. Brit. 93. Supp. 37. t. xvi. 
f.1; M. & R. Trans. Linn. Soc. vii. 71 ; Flem. Edinb. 
Encycl. vii. 93 ; Dill. Dese. Cat. 141; Turt. Conch. Dict. 
82. 
This species is very common on the coasts of Devon, Corn- 
wall, South Wales, south of Ireland, and in the Isle of Arran 
opposite Lamlash Island. 
3. MACTRA TRUNCATA. 
Shells wedge-shaped, concentrically striated ; striee irregular. 
Length an inch and five-eighths ; height one inch and a half. 
Colour more or less tinged with reddish, inclining to rust. 
It occurs in great abundance in the Kingsbridge Estuary, and 
is sometimes found in the Frith of Forth. 
Mactra truncata, Mont. Test. Brit. Supp. 34; Flem. Edinb. 
Encycl. vii. 93; Dill. Dese. Cat. 140; Turt. Conch. Dict. 
81? 
Mactra crassatella, Zam. Hist. Nat. des Anim. sans Vert. v. 
479. 
It may readily be distinguished from Mactra solida by its 
superior height in proportion to its length. I have carefully 
measured a vast number of specimens of each species, and they 
have given the mean result. 
4. MACTRA SOLIDA. 
Shells ovate-triangular, striated concentrically; the stric 
irregular. 
Colour testaceous, yellowish or dirty white; inside white 
and glossy. Length one inch, seven-eighths ; height eleven- 
eighths. 
Mactra solida, Linn. Syst. Nat. xii. 1126; Penn. Brit. Zool. 
ive, 92. t. In. f. 43...t.. 5 ;.Mont.. Test. Brit) 92 3. Flem: 
Edinb. Encycl. vii. 93; Dill. Desc. Cat. 140; Lam. Hist. 
Nat. des Anim. sans Vert. v. 477; Turt. Conch. Dict. 81. 
