MACTRA. 
81 
t 4. Mactra Stultorum. Simpleton's Mactra. 
Lister , pi. 251. f. 85— Pennant, pi. 52. f. 1— Da Costa 
pi. 12. f,3— Donovan , pi. 106— Dorset Cat. pi. 8. f. 3. 
Shell somewhat triangular, ver}* thin, brittle, and semi- 
transparen: ; covered with a thin skin, very convex, faintly 
striate transversely, grey or pale rufous brown, more or 
less distinctly radiate longitudinally with broader and .nar¬ 
rower whitish stripes ; the posterior slope produced in the 
middle into ail acute keel-like ridge : beaks central, large, 
prominent, frequently of a purplish hue; the lateral teeth 
of one valve double : length an inch and a half; breadth an 
inch and three quarters. 
V iriettj. Of a greyish color, more or less tinged with 
purple both inside and out, rather wider in proportion to its 
length, without the longitudinal rays, but very roughly 
wrinkled and brown on the anterior slope, not so large, and 
of a more glossy appearance. 
Mactra cinerea. Montagu, Suppl. p. 35. 
On most sandy shores: the variety very common in the 
north of Devon, v. v , 
i 5, Mactra solida. Solid Mactra . 
Pennant, pi. 55. f. 2— Da Costa, pi. 15. f. 1— Donovan y 
pi, -61 — Dorset Cat. pi. 12. f. 1. 
Shell strong and solid, opake, convex, roundish, equal at 
the sides, nearly smooth, with a few antiquated transverse 
ridges i yellowish-white, with often yellowish or blueish 
transverse bands ; within glossy white: beaks central ; 
primary teeth small; lateral-teeth strong, striate within, in 
one valve a deep groove behind the lateral ones, but not din 
rinctly double as in the last; length an inch and a half ; 
breadth two inches. 
Sandy and gravelly shores, v. v. 
6. Mactra troncata. IVedgc-shapcd Mactra. 
Lister, pi. 253. f. 87— Da Costa, pi. 14. f. 6 — Dorset 
Cat. pi. 6. f. 6. 
Mactra subtruncata. Donovan, pi. 126. 
Shell strong, thick, opake, very convex, triangular, 
nearly smooth, but mostly marked with a few faint distant 
transverse 
