TESTACEOUS MOLLUSCA. 28 1 



large, and in the lower valve very strongly emarginated ; ribs of 

 the left valve from 9 to 13, thick, irregular, unequal, armed with 

 coarse subquadrate scales, the interstices with irregular radiating 

 sulci; of the right valve numerous and squamiferous. 2|. Japan. 



P. Lividtjs. Lam. 58.— Sow. Th.f. 61, 89, 91.—^. t. 76, 

 /. 4, 5, G.—Var. P. Sulphurea. Lam. 57.— Ch. f. 629. Irre- 

 gular, suboval, subequivalve, compressed, foliaceous ; ears unequal, 

 large, the posterior the larger and in the lower valve very strongly 

 notched; with from 16 to 20 ribs which are unequal, scarcely 

 raised, and armed with numerous acute scales, the interstices with 

 irregular radiating sulci ; variegated purplish brown, with the 

 scales white or yellow. Variety. Scarcely mottled. Variety. 

 Yellow. 2J...2|. . .Red Sea and Japan. 



P. Squamosus Sow. Th.f. 48, 49, 50, 88, 92, 93.— Ostrea, S. 

 Gmel. — List. t. 184, /. 21. — P. Hybrida (m part) Lam. 56. 

 Variety B. — P. Araucisantjs. Ch.f. 630, 1. Irregular, suboval, 

 subequivalve, flat, foliaceous ; ears large, unequal, the posterior the 

 larger, and in the lower valve very strongly notched; variable in 

 coloring (often marked with fine ziczac lines of white, with from 

 12 to 18 almost obsolete, scaly ribs, which grow faint at the umbones, 

 and in the lower valve are numerous and very slightly angulated. 

 2 T : \ y ... ■l-JJ... Northern Ocean. 



P. Serratus. Sovj. Th. f. 56. Obliquely oval, irregular, an- 

 teriorly somewhat produced, rather compressed ; the ears unequal, 

 the anterior the smaller ; sulphur coloured, with large brown spots, 

 the ribs numerous and most minutely scaly : inside purple at the 

 margin. IJ^.,14. Philippines. 



P. Irregularis. Sow. Th. f. 51, 2. Obliquely oval, subin- 

 equivalve; ears unequal, with scabrous sulci, the anterior small 

 and obtuse, the posterior large and acute ; scarlet with seven rays 

 of interrupted white, mottled with purple ; ribs numerous, small, 

 scabrous, and subangulated. l^j...£ 



P. Squamatus. Sow. Th.f. 57, 58.— Gmel. 3329.— Lis. t. 183,/ 

 20. — P. Rastellum. Reeve. Sys. 1. 114:*, f. 3. Rounded, subtrian- 

 gular.compressed, irregularly subequivalve, upper valve very slightly 

 the more convex ; ears large and costated, with pointed scales, the 

 posterior broad and somewhat acutely angulated ; dull clouded 

 brown, with, in one valve, from five to seven red broad rounded 

 irregular ribs, which are armed with pointed scales, and fifteen 

 smaller interstitial ones, the interstices most minutely punctated ; 

 in the other valve the ribs are irregular, scaly, and unequal. HJ 

 ...l*. There is a white variety. 



P. Bruei. Payr.p. 78, t. 2 ? /. 10, U.—Sow. Th. f. 241,2. 

 Suborbicular, equivalve, subequilateral, yellow ; rays of the upper 



