TESTACEOUS MOLLUSCA. 277 
P. Danicus*. Chem. f. 2043.—Sow. Th. f. 16. §° 187.—E. ¢. 
212. f. 6.—P. Asprrsus. Lam. 17.—Ostrrea Hysripa. Gmel. 
3318.—D. p. 251.—O. Trirapiata. W.t. 11. f. 39. Variety. P. 
Psrupamusium. Ch. f. 601,2.—Ostrea H. W. t. 10. f. 10. Com- 
pressed, nearly circular, subequilateral, smooth or with obsolete 
radiating strie; pale red, sprinkled with crowded minute irregu- 
lar darker spots, with seven broad scarcely raised angular ribs 
which are fainter near the margins. 13...13. Scotland, Denmark. 
P. Distans. Lam. 25.—Sow. Th. f. 182.—Knorr. 2.t. 18. f. 
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. Rastettum. Lam. 14.—Sow. Th. f. 30.—Del. t. 16.f. 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. 14 
«12. Northern Seas. 
P. Pictus. Sow. 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. 43...4 Isle of Baccus. 
P. Supersus. 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 airs -three thick rounded and 
smooth ribs, the interstices narrow. 2d. 
P. Histrionicus. Lam. 32.—Sow. Th. rf '240.—Reeve. t. 114*. 
f. 1.—Ostrea H. Gmel. 3326.—Ch. f. 614.—W. t. 10. f. 20.— 
Knorr. 4. t. 12. f. 3.—E. t. 213. f. 8.—Ostrea Suncata (partly). 
D. p. 255. Obliquely suboval, compressed, subequivalve, lower 
valve the more ventricose; the auricles striated, the anterior the 
smaller the posterior emarginated 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 semeed at the sides, the three lateral ribs 
