BO 
MACTRA. 
angular^ and a small cavity each side ) the lateral 
teeth remote, and lockinginto the opposite valves, 
1. Mactra dealbata. Pellucid Alactra. 
Montagu, pi. 5. f. 1— Linn. Trans, viii. pi. 1. f. 10— Don 
set Cat. pi. 7- f- 7- 
Shell oval, thin, brittle, transparent, white, very finely 
Striate transversely, with a few coarser wrinkles, gaping 
and very slightly produced at the smaller end, but well 
rounded at both ; within glossy-white, a little concave, with 
a plain sharp margin : beaks a little oblique, not quite cen¬ 
tral ; the middle tooth in one valve broad, forked, angular 
close to the beak : length an inch and a half j breadth nearly ( 
txvo. 
At the mouths of rivers : rare. v. «n. 
2. Mactra glauca. Glaucous Mactra . 
Donovan, pi. 125. 
Shell oval, dirty white, thin, semitransparent, finely 
striate transversely and wrinkled at the anterior end, mark¬ 
ed with broad and narrow longitudinal glaucous rays: 
beaks reflecting backwards, with a narrow gape between 
them: length nearly two inches and a half; breadth three 
and a half. 
Found by Miss Pocock, in Cornwall: very rare. 
3. Mactra radiata. Radiated Mactra . 
Donovan, pi. 161. 
Cardium edentulum. Alontagu, Suppl. p. 29. 
Shell thin, brittle, somewhat triangular and produced at , 
one end, ash-color, paler and with a light flesh-color tinge 
beneath the skin, very faintly and obscurely striate longi¬ 
tudinally, with a few broad faint distant transverse wrinkles, 
and marked with numerous equidistant narrow pale testa¬ 
ceous longitudinal rays ; inside smooth, white, with a plain 
margin, the outer striae being risible in the thin part: beaks 
pointed, nearly central; turning a little to one side; pri¬ 
mary teeth none, but immediately under the beaks is a 
small depression, with the rudiment of a small denticle, and 
a little remote on each side is a small laminar tooth: length 
two inches and a half; breadth three inches. 
Found by Captain Laskey, at Portsmouth: very rare. 
4. Mactra 
