TRIBE MYARIA. 23 



A. NicoBAKiCA. Orai/.—Mw N. Gmel. 3221.— Z>. j). 44.— 

 Ch. f. 17, >i.— \Vood. G. C. p. 97.— TF. (. 2./. 11 —Ovate ob- 

 long, white, equivalve, with decussated striae ; 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. 1^.. If. — Nicohar Isles. - 



A. Globosa. Gray.— M.Yk G. Wood. G. C. p. 95. t. 24. /. 

 4, 5, 6. — D. p. 44. — W. t. 2.f. 5. Suborbicular, with transverse 

 strise decussated by longitudinal ones on the anterior side only : 

 hiatus terminating in a sharp reflected margin. — diam. |. 



A. CosTATA. Sorv.Z. P. 1834. Oblong, white, anteriorly beaked, 

 posteriorly rounded ; with 8 radiating ribs, becoming smaller towards 

 the posterior end. 2_-3_ — Ainerica. Inform like long irostris. 



A. Elliptica. Kintf inZ. J. 5.— Grif. Cuv. Mol t. 22. f. 3. 

 Elliptic, rather thin, transversely striated, posteriorly subtruncated : 

 the epidermis brown and thin. \^..2^. — New S. Shetland.^ 



A. Pr^tenius* Turt. B.p. 48. t. A.f. 4.— Mya P. Pen. A. p. 

 160. t. 50./. \.—Don. 5. t. 176.— TFoor/. G. C. p. 94. t. 24./. 7, 

 8, 9.— Dor. Cat. t. A.f. 7.— W. t. 2./. 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 . . 1^. — lEngland. 



A. Distorta.* Turt. Biv.p. 48. t. 4. /. 5.— Mya D. 3Iont. 

 ]). 42. t. \.f. 1. — W. t. 2. /. 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. |. — England. 



A. Papyracea. Say. Jour. A. N. S. Phil. 2. p. 314. — Sil. 

 J. 28. p. 347. / {.—'Gould. Mas. p. 48. /. 28. Turgid, very 

 thin, ovate, one valve very convex and its ventral edge projecting 

 shghtly beyond the other ; beaks not prominent, placed near one 



2 A. Membranacea. Gray.— Mya M. Gmel. 3222.— D. /;. 48. 

 — Olaffsen. Isl. res. 2. p. 2."^. 11. / 10.— TF. t. 2./ 14. Oval, 

 membranaceous, white, produced on one side so as to form a beak ; 

 margin reflected ; hinge toothless . 1 . — Iceland. 



We have copied the original figure of this specie.^, but are unable 

 to identify the shell. 



3 Closely allied if not identical is the A. Prismatica. 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. \4;..2-^'fy — New 

 S. Shetland. 



