TRIBE OSTRACHA. 313 
foreign substances, seemingly ribbed, tuberculated, &c., but never 
with sculpture regularly radiating from the beaks), white, orange- 
yellow or reddish violet: perforation for the most part large: sub- 
central scars 3, the upper large, the two others rather smaller, 
subequal, one above the other, the lower of the two rather more 
behind. 24. Hurope.t Van.? from New York. Upper valve 
wholly or partially yellow; lower valve green. Looks like Philippi’s 
Jigure of A. Peruviana (N. C. 3, An. t. 1, f. 2, 8). 
A. Acutgata.* Miil—Gm. 3346.—Brug. 73.—Mont. 157, t. 4, 
F.5—Gould, Mas. p. 139, f. 90.—Brit. Mar. C. f. 73.—Brit. Mol. 2, 
p. 332, pl. 55, f. 4.—A. Srriotata, Turt. B. p. 233. Suborbicular, 
resembling the last species, but small, never coloured either within 
er without, and always armed in one or both valves, with most 
crowded series of prickly strive, which emanate from the beaks, and 
radiate most regularly to the margin. 4. Britain, dc. 
A. Ainiematica.—Teiiina Al. Ch. f. 1949, 50.—A. Rosea, Gray, 
Ann. Ph. 1825.—A. Al. Wieg. Arc. 1837.—Gray, Cat. An. p. 20.— 
Ainiama R., Kust. Ch. vii. pt. 1, t. 7, f. 1 to 7. Transverse, oval or 
oblong (more rarely cylindraceous), thin, compressed. Upper valve 
of an uniform purple or more rarely yellow tint, smooth, or with a 
few obsolete radiating ribs ; apex acute, considerably within the dorsal 
edge, a rudimentary linear notch in the margin above it; upper sub- 
central scar rather large, the two lower ones smaller, equal-sized, 
nearly confluent. Lower valve very much paler; perforation small, 
remote from the edge; one lobe overlapping the other. 13. Singa- 
pore; Philippines.3 
A. Lampe. Gray, Z. P.1849, p.117; Cat. An. p. 19.—Carpenter, 
Mazatlan Shells, p.167. Thin; upper valve yellow (rarely salmon- 
coloured), radiatingly ribbed; apex submarginal; lower valve white, 
t The two following, with the A. Pectinara of Bruguiére (Ch. 698, 
690), and his A. Srriaruna (for Ch. f.697), are probably forms of the 
same polymorphous shell :— 
A. MemBranacea. Lam. 7.—EH.t. 170, f. 1,3? Rounded, flat- 
tened, so excessively thin as to be almost membranaceous: back of 
the larger valve yellowish, obsoletely ribbed. 14. 
A. Luns. Lam. 9. Minute, obliquely elliptic; pierced valve a 
little convex; perforation small, oblong; umbo of the other valve 
acute. Hurope. 
2 Philippi regards the A. AcuLrara of Loven as a distinct 
species, and has termed it A. Venusta (N. C. 8, An. t. 1, f. 5). 
3 Compare with this the A¢n. Revicunarum, CorruGatum and 
ConvexuM of Koch, in Hust. Ch. vil. pt. 1, #. 7. 
Z 

