TRIBE PECTINIDES. 271 
(besides some smaller and rather elevated ones at the sides) which 
are narrow and distant, the interstices broad and flat; lower valve 
very ventricose, its margin overlapping the other, its ribs broad 
smooth and without interstices. China, Australia, Zebu, Se. 
21..,.22. 
*p, Asprr. Sow. Th. f. 196,7.  Suborbicular, rather com- 
pressed ; ears broad, obsoletely striated, those of the lower valve 
serrated at the margin; upper valve somewhat flattened, slightly 
elevated towards the umbones; ribs eighteen, angulated, biangu- 
lated towards the margin, the angles serrated, and the interstices 
narrow flat and concentrically striated; lower valve ventricose, 
the eighteen ribs rounded, angulated at the umbo, and concentrically 
striated, the interstices narrow and flat; upper valve pale red, 
with minute red concentric touches on the ribs and bands in the 
interstices, these being less numerous in the lower valve (whose 
ribs are interlineated and the umbo tinted with red) leave it almost 
white. 14...12. New Guinea. 
P. Inxauivatvis. Sow. Th. f. 193, 4, 5. Suborbicular, rather 
compressed, oblique, spreading on one side, concentrically striated ; 
ears small and nearly equal; upper valve somewhat flattened, 
slightly elevated towards the umbones, grey spotted with blackish 
brown and black, the eighteen ribs elevated subangulated, the in- 
terstices narrow and flat ; lower valve ventricose, reddish white, spot- 
ted with brown on the eighteen efevated and rounded ribs, which are 
subquadrate near the margin, the interstices narrow and flat, the 
anes spotted with grey. Variety. Lower valve spotted with red. 
14, 1,3,. Philippines. 
Asrersus. Sow. Zool. P. 1835.-—-Sow. Th. f. 198,9 (not 
Laie) Suborbicular, rather depressed, subequivalve, equilateral ; 
the ears unequal, the lower rather large; one valve white or pale- 
ish, its fifteen ribs larger rounded and smooth; the fifteen more 
acute ribs in the other, fuscous sprinkled with small bluish dots, 
the rather pale interstices most delicately striated longitudinally. 
1,3,...12. Peru. 
P. Nucreus. Born. t.7.f.2.—Sow. Th.f.85.—P. Turerpus. 
Lam. 15.—Osrrea T. Gmel.—D. p. 268.—W. t. \1. f. 47.— 
List. t. 169. f. 6. Orbicular, ventricose, subequivalve, thick, 
grey clouded with greyish brown, or nearly white clouded with 
reddish brown; ribs eighteen to twenty, elevated subquadrate, 
concentrically striated, the interstices oe agra ee small, 
nearly equal, grooved, rectangular. 1,%...12. {iga}- bus 
P. Crrcutaris. Sow. Z. P. 1835.—Sow. Th. a5 98, Suborbi- 
cular, tumid, subequivalve, equilateral, variegated with brown and 
white; ears large and nearly equal; radiating ribs eighteen, the 
