284 TRIBE PECTINIDES. 
O. Nucievus (npart.) D.p. 267. Oval subtriangular, ventricose, 
equivalve, equilateral, thick ; ears unequal and sulcated, the anterior 
moderate and straight, the posterior larger and acute: uniform 
orange, or nearly white with large defined brown patches; with 
eighteen nearly smooth elevated squarish ribs, whose sides are most 
minutely serrated. 12...14,. Tranquebar. 
P. Sincaportnus. Sow. Th. f. 55 and 71. Rounded subtri- 
angular, rather compressed, equivalve, equilateral, rather thin; 
ears unequal, the posterior large; white tinged with pink, with four 
broad brown lineated rays, the twenty-four ribs elevated sub- 
quadrate and smooth, spotted with grey near the umbones 
1,4,---13)- Stngapore. A much greater number of less elevated 
ribs than in the preceding. 
P, Senatorius. Lam. 44.—Sow. Th. f. 151, and 188 to 191. 
—Ostrea, 8S. Gmel. 3327.—D. p. 256.—W. t. 10, f. 22.—Ch. 
J. 617.—E£. t. 211, f. 5.—O. Porpuyrea. Gmel.—D. p. 260.— 
Ch. f. 632.—W. t. 10, f. 30.—P. Aurantius. Lam, 45.—O. 
Citrina. Gmel.—W. t. 10, f. 23.—D. p. 257.—Ch. f. 618.— 
P. Frorens. Lam. 46.—Del. t. 15, f. 6. Oval subtriangular, 
rather depressed, equivalve, nearly smooth, anterior side very 
slightly spread ; ears unequal, the anterior usually obtuse, the pos- 
terior elongated and emarginated at the base ; ribs from twenty to 
twenty-four, rather elevated, smooth or minutely serrated, armed 
with annular scales which are crowded at the sides: colour ex- 
tremely variable. 2...147. Indies, Moluccas, Red Sea. 
P. Crassicostatus. Sow. Th. f. 111, 152. Suborbicular, 
thick, subequilateral, nearly smooth; ears unequal, rayed with 
squamular ribs; pale purple or orange, with twenty-four thick ele- 
vated squarish annulated ribs, the lateral armed with scales, the 
interstices nearly smooth: white within. 43,...42. Larger than 
the preceding, with tts ribs more square and elevated. 
P. Istanpicus. Lam. 42.—Sow. Th. f. 159, 160, 161.—Gould. 
Mass.—Ostrea, T. Gmel. 3326.—W, t. 10, f. 21.—O. Crn- 
NABARINA. JD. p. 256.—Ch. f. 615, 6.—E. t. 212, 7. 1. Oval, 
rather compressed, subequivalve, subequilateral, thin, very slightly 
spread anteriorly ; ears unequal, with scabrous pe the posterior 
large ; orange with concentric bands, or white or purple with con- 
centric and radiating bands, the extremely crowded irregular unequal 
serrated ribs grouped together i in twos, threes, or fours. 3}...3. 
N. Ocean. 
P. Asperrimus. Lam. 43.—Del. t. 15, f. 1.—-Son. Th. f. 156, 
7, 8.—Osrrea, A. W. S.t.2,f.1. Rounded suboval, ventricose, 
thin, equivalve, inequilateral, with scabrous sulci, anteriorly rather 
spread ; ears unequal, with scabrous sulci; reddish brown, orange, 
