TRIBE MYARIA. 23 
A. Nicoparica. Gray.—Mya N. Gmel. 3221.—D. p. 44.— 
Ch. f. 17, 8.—Wood. G. C. p. 97.—W. t. 2. f. 11 —-Ovate ob- 
long, white, equivalve, with decussated striz; convex broad and 
rounded at one end, at the other attenuated, subtruncated, flat and 
gaping : hinge subcentral, the spoon-shaped tooth broad and per- 
pendicular. 14.. 13.— Nicobar Isles.* 
A. Guogosa. G'ray.—Mya G. Wood. G. C. p. 95. t. 24. f. 
4, 5, 6.—D. p. 44.—W. t. 2. f. 5. Suborbicular, with transverse 
strize decussated by longitudinal ones on the anterior side only : 
hiatus terminating in a sharp reflected margin.—diam. 3. 
A. Cosrata. Sow. Z, P. 1834. Oblong, white, anteriorly beaked, 
posteriorly rounded; with 8 radiating ribs, becoming smaller towards 
the posterior end. 2,3.—America. In form like Longirostris. 
A. Exuiptica. King in Z. J. 5.—Grif. Cuv. Mol. t. 22. f. 3. 
Elhptic, rather thin, transversely striated, posteriorly subtruncated : 
the epidermis brown and thin. 13..22.— New S. Shetland. 
A. Prarentus* Turt. B.p. 48. t. 4.f. 4.—Mya P. Pen. 4. p. 
160. t. 50. f. 1.—Don. 5. t. 176.— Wood. G. C. p. 94. t. 24. f.7, 
8, 9.—Dor. Cat. t. 4. f. 7.—W. t. 2. f.5. Oval-oblong, subequi- 
lateral, depressed, white, rounded at both ends, anteriorly attenuated ; 
dorsal edges sloping, the ventral sub-anteriorly incurved : teeth oval 
and horizontally projecting inwards. 1..14.— Hngland. 
A. Distorta.*  Turt. Biv. p. 48. t. 4. f. 5—Mya D. Mont. 
p.42.t. 1. f.1.—W. t. 2. f. 15.—D. p. 45. Convex, very variable 
in shape, being orbicular oblong or kidney-shaped, with the margin 
variously indented not rarely entire; teeth rounded and projecting 
inwards. 3.— England. 
A. Papyracea. Say. Jour, A. N.S. Phil. 2. p. 314.—Sil. 
J. 28. p. 347. f. |.— Gould. Mas. p. 48. f. 28. Turgid, very 
thin, ovate, one valve very convex and its ventral edge projecting 
slightly beyond the other ; beaks not prominent, placed near one 

2 A. Mempranacea. Giray.—Mya M. Gimel. 3222.—D. p. 48. 
—— Olaffsen. Isl. res. 2. p. 2. t. 11. f. 10.—W. t. 2. f. 14. Oval, 
membranaceous, white, produced on one side so as to form a beak ; 
margin reflected ; hinge toothless. 1.—Jceland. 
We have copied the original figure of this species, but are unable 
to identify the shell. 
3 Closely allied if not identical is the A. Prismarica. Sow. Z. 
P, 1834. Oval, subtrapeziform, thickish, opaque, with the nacre 
prismatic ; posterior side truncated, the gape very large : an internal 
subumbonal lamella in each valve, running downwards from the 
tubercle which supports the ligament, with a branch of the horny 
ligament almost parallel to it, posteriorly inclined. 14..2;3,.— New 
S. Shetland. 
