TESTACEOUS MOLLUSCA. 277 



P. Danicus*. Chem.f 2043.— Sow. Th.f. 16. #■ 1S7.—E. t. 

 212. /'. 6. — P. Aspersus. Lam. 17. — Ostrea Hybrid a. Gmel. 

 3318.— D. p. 251.— 0. Triradiata. W.t. 10?./. 39. Variety. P. 

 Pseudamusium. Ch. f. C01 ,2.— Ostrea H. W. 't. 10./. 10. Com- 

 pressed, nearly circular, subequilateral, smooth or with obsolete 

 radiating striae; pale red, sprinkled with crowded minute irregu- 

 lar darker spots, with seven broad scarcely raised angular ribs 

 which are fainter near the margins. 1J-...1|-. Scotland, Denmark. 



P. Distans. Lam. 25.— Sow. Th.f. l82.—I(norr.2.t. 18. /. 

 5. — Gualt. 74. a.b. Nearly oval, rather compressed, subequi- 

 lateral, radiatingly striated ; hinge obliquely plicated ; ears nearly 

 equal, the posterior emarginated at the base : light cream-coloured 

 with spots and bands of a very dark brown, the ten ribs rounded, 

 elevated and thick; brown within. 1,87... 1,54. Philippines. 



P. Rastellum. Lam. U.—Sow. Th. /. 30.— Bel t. 16./. 1, 

 2, 3. Rounded, compressed ; the ears large, radiatingly striated* 

 and emarginated at the base, with erect sharp scales on the edges. 

 Ribs nine, gradually shelving down, the three central ones rather 

 large and rounded, with small triangular scales on the top, the 

 lateral ones rather smaller and angulated, the scales on the extreme 

 ones sharp and erect : orange with angular brown spots on the 

 interstices and the sides spotted, or white with brown spots, li 

 ...1^. Northern Seas. 



P. Pictus. Soiv. Th. f. 233. Obliquely ovate, compressed, 

 striated at the sides ; ears nearly equal, (the edge of that of 

 the under valve serrated,) radiately striated, emarginated at the 

 base ; dull white variegated with broad irregular bands fine trans- 

 verse lines and spots of red ; the thirteen ribs square at the top 

 with slanting sides, the interstices narrow, defined by two small 

 grooves and crenulated : inside white, ^l"-^ Isle of Baicus. 



P. Superbus. Sow. Th. f 11. Suboval, oblique, anteriorly 

 spread, flat, solid ; ears small and obtuse ; pale straw coloured, 

 pale pink near the umbones, variegated with interrupted angular 

 bands of brightish red ; with twenty-three thick rounded and 

 smooth ribs, the interstices narrow. 2f ...2-|. 



P. Histrionicus. Lam. 32.— Sow. Th.f 240.— Reeve, t. 114*. 

 /. 1.— Ostrea H. Gmel. 3326.— Ch.f. 6U.— W.t. 10. /. 20.— 

 Knorr. 4. t. 12. /. 3.—E. t. 213./. 8.— Ostrea Sulcata (partly). 

 D. p. 255. Obliquely suboval, compressed, subequivalve, lower 

 valve the more ventricose; the auricles striated, the anterior the 

 smaller the posterior emai'ginated at the base ; nearly white, 

 in the upper valve some of the ribs spotted with red, the in- 

 termediate with black, the seven central ribs broad rounded 

 smooth on the top and serrated at the sides, the three lateral ribs 



