TRIBE PECTINIDES. 269 



obliquely plicated ; with from twelve to fourteen somewhat depressed 

 rounded ribs which are broad and sulcated, yellowish white or yel- 

 lowish brown, angularly spotted (chiefly at the umbones) with red 

 or brown. 6 . . 6|. England, Mediterranean. The common Scallop 



P. Similis Sow. Th.f. 116,7. Closely resembling the last, but 

 the ribs in the concave left valve more elevated, in the smoothish 

 right valve more grooved. 3f..3^ England.? 



P. Jacob^eus* Clum.f. 588. — Lam. 3. — Phillippi. p. 78.—Poli. 

 t. 27../. 1, 2, 3.—E. t. 209./. 2.— Sow. Th. f. 107, 108, 153.— Os- 

 trea J. Lin. 1144.— Zi^. t. 165.— W.t. Id./. 2. Suborbicular, 

 spread at the sides, rather depressed ; upper valve concave near the 

 umbo, the sides elevated; ears broad rectangular concave and grooved 

 near the margin ; ribs fourteen to sixteen, in the left valve much 

 elevated rounded concentrically striated, in the lower valve much 

 elevated, quadrate, with strong radiating moniliform sulci, the 

 interstices concentrically striated ; yellowish white or yellowish 

 fuscous, angularly spotted with red or fuscous. 6. . 6|. England? 

 Mediterranean. 



P. Laqueatus Sow. Th. t. 15. / 101. Rounded; right valve 

 with seven broad somewhat smooth subquadrate flattened ribs, which 

 are obsoletely and radiatingiy grooved ; the interstices narrow, flat : 

 white, tinged with purple at the umbo. N. W. America. 3\. . 4-*-. 

 The other valve is unknown. 



P. Medius Lam. 2. — E. vol. 3. p. 715,— Sow. Th.f. 102, 3,4. 

 — Ch. f. 586, 7, 8. ? Suborbicular, rather depressed, smooth ; 

 flattened valve rather concave near the umbone, sides slightly ele- 

 vated, with fourteen narrow ribs which are angulated at the sides 

 and flat; ears equal, broad, concave and grooved near the margin : 

 ribs in the convex valve sixteen, broad, divided, somewhat rounded, 

 depressed ; yellowish white or fuscous with red spots, red with 

 either white spots or purple bands. '3,3. .2, 8. W. Lndies. 



P. Sulcicostatus Sow. Th.f. 35,6. Rounded, radiately sul- 

 cated, rather ventricose ; ears wide, concave, striated ; the ribs twelve 

 in the upper valve, (which is pale fawn witli angulated streaks of 

 red,) elevated, rather square and sulcated ;in the purple lower valve, 

 rounded and striated, with scarcely any interstices ; interstices of 

 the left valve sulcated and as wide as the ribs. 1^. . -i~§ 



P. Subviridis Sow. Th.j '. 165,6. Suborbicular, subventricose ; 

 upper valve concave near the umbones, the sides elevated ; ears 

 broad rectangular, concave and grooved near the margin, the thirteen 

 central ribs rounded smooth and elevated in the upper valve, the 

 lateral ones smaller ; in the lower valve obsoletely grooved, the 

 interstices concentrically striated ; upper valve greenish brown, 

 lower valve white, yellow at the umbo, and brownish in the middle. 

 2. . 2^ Allied to Javobceus, 



