MYA. GAPER. 
107 
the margin, irregularly striate transversely, a little con¬ 
tracted or indented opposite the hinge on the front mar¬ 
gin: beaks much worn and rugged, appearing as if worm- 
eaten; inside perlaceous mixed with green, and often 
rough with pearly excrescences : hinge with a strong erect 
tooth in one valve, locking between a widely cloven one in 
the other: length nearly two inches, and four in breadth. 
In rapid rivers, v. v. 
23. Mya inmquivalvis. Unequal Gaper. 
Montagu, pi. 26. f. 7— Linn, Trane, viii. pi. 1. f. 6—* 
Wulkcr, f. 85. 
Shell somewhat triangular, produced on one side, strong, 
convex, opake, covered with a brown skin, under which it 
is white with frequently a flesh-colored skin, the younger 
ones marked with pale or flesh-colored rays ; one of the 
valves much larger, regularly striate transversely with a 
few deeper grooves, and folding over so as to receive the 
smaller one; the lesser valve obscurelystriate transversely, 
with a few longitudinal raised lines : beaks prominent, gib¬ 
bous; that of the larger valve turning over and meeting 
the other : hinge with a strong pointed recurved tooth in 
the larger valve, and a cavity; in the lesser valve is a 
spoon-shaped tooth projecting inwards, having a raised 
denticle at the posterior side, and a cavity, all locking into 
each other; inside smooth, polished at the edge: length, 
about a quarter of an inch; breadth not half an inch. 
Western coasts, Scotland, Dublin bay. v. v . 
24. Mya Glycymeris. Great Gaper. 
Litter , pi. 414. f. 258— Donovan , pi. 142— JVood, pi. 25. 
U. 
Shell large, coarse, lamellar, oblong-oval, irregular at 
the margin, open at both ends, with regular waved trans- 
1 verse ridges disposed like bands, and marked with line 
I striae, obliquely truncate at the anterior end : color yellow- 
uh or ochraceous, whitish within: beaks nearly central, 
slightly indented both sides : hinge with a large thick tooth 
in one valve, besides a lesser one and a series of wrinkles, 
closing into a cavity in the other valve: length four or five 
inches; breadth eight or nine. 
