276 TRIBE PECTINIDES, 
nearly equal, substriated ; upper valve more ventricose, overlapping 
the margin of the other, the five ribs broad and rounded; lower 
valve with four broad ribs which are almost in pairs ; colouring very 
variable, being orange or purple, either uniform or mottled, 
yellow variegated with grey and intermediate rays, and greyish 
with zebra-like markings of brown. 1,3,...143. <Adriatie. 
P. Sutcatus. Lam. 21.—Sow. Th. f. 179,180. 1.—Philippi. 1 
p.79.—OstrEA S. Born. t, 6. f. 3.—D. p. 255. (partly).—P. 
Fraviputus. Lam.—P. Soraris. Ch. f.638.—Ostrea,S. W.t 
10, f.40. Orbicular, rather flattened, with radiating striz ; ears 
nearly equal, broad and acutely angulated ; orange colour, blackish 
brown or nearly white with brown spots; with ten ribs which are 
grooved, rounded elevated and equal 14..1},. Mediterranean. 
P. Unicotor. Sow. Th. f. 5, 6.—Lam. ? 23.—Reeve. Sys. t 
114. fi 5 ?—Regenf. t. 11. f. 50 ?—Knorr. 1. t. 8 f. 5? 
Rounded, rather irregular, inequivalve, rather ventricose, rather 
smooth ; ears nearly equal and striated; upper valve the more 
ventricose and overlapping the margin of the other, its nine ribs 
rather distant, rounded and somewhat depressed; lower valve 
rather flat, its ribs less elevated; plain orange, or pale red with 
concentric bands of light brown. 14...145. Black Sea. 
P. Frexvosus. Lam. 38.—Sow. Th. f. 200 to 205.—Osrtrea F. 
Poli. 2.t. 28.7.1, 2,5, 11.—P. Potymorrpuus. Jay.—Philippi.p. 79? 
—P. Isasenia. Lam. 26. Subequilateral, rounded-fanshaped, 
more or less ventricose, smooth or with obsolete radiating striae, 
the margins usually inflected ; ears nearly equal, radiated, straight, 
acutely angulated, emarginated at the base; with five large gradu- 
ally elevated ribs, sometimes with five small intermediate ones ; 
variable in colouring : internal ribs in pairs, dentated at the margin. 
3.4.4. Mediterranean. 
P. Unpusatus. Sow. Th. f. 206,7. Very like the last, but 
the sides more spread, the margins angularly inflected, the ribs 
more elevated: upper valve yellowish red, purple internally ; 
under valve white, tinted with rose. 1+..1,%;. Mediterranean ? 
P. Erevatus. Sow. Th. f. 14, 15. ‘—-Ostrea Exrvara. Poli, 
t. 28. f.17.& O. Inrrexa. f. 4,5? P. Aspersus. Philippi. p. 81? 
Rounded subtriangular, inequivalve, subequilateral, depressed, 
most minutely cancellated, the umbones acuminated, the ventral 
margin denticulated and usually inflexed ; ears small, the anterior 
the less; upper valve slightly hollowed in the centre, with five 
large elevated gradually depressed ribs, which near the umbones 
are angulated, near the margin inflated; extremely pale rufous, 
variegated with small red and radiating brown spots; lower valve 
white, rather ventricose, with four large broad rounded and elevated 
ribs. 14...1-3,. Sicaly. 
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