272 TESTACEOUS, MOLLUSCA, 
interstices broader and with curved strize; the sulci deeper in one 
of the valves. 12...14. St. Vineents and California. 
P. Venrricosus. Sow. Th. f. 18,19,26.—P. Tumipus. Sow. 
Z. P. 1835. Subinequivalve, equilateral; ears large and nearly 
equal, one valve turgid, variegated with reddish brown and whitish, 
with eighteen radiating ribs which are flattened on the top. and 
have their interstices longitudinally striated; the other valve more 
turgid, whitish with radiating sulci; the interstitial ribs broader 
and flattened, the lateral variegated with brown: ventral edges 
acutely dentated. 13...13. W. Columhia. 
P. Irrapians. Lam. 37.—Sow. Th. f. 139, 140.—Del. t. 15. 
jf. 4.—P. Turetpus. Sow. G.—P. Concentricus. Say. Orbicu- 
lar, ventricose, rather thin, with minute concentric striz ; ears 
nearly equal, striated, one side smaller and emarginated at the base ; 
pale reddish yellow, nearly covered by broad bands and large 
patches of greyish and reddish brown, a large portion being left 
nearly white in the lower valve; the eighteen ribs are rounded, with 
wide interstices. 34...34. Mediterranean and Newhaven. 
P. Purruratus. Lam. 11.—Del. t. 16. f. 5.—Sow. Th. f. 113, 
123,125. Orbicular, spread at the sides, ventricose, thick; ears 
nearly equal, with radiating ribs, emarginated at the base; pale 
purple with strongly marked festoons of white and blackish brown, 
(a variety also is orange, and even white) on the twenty-two broad 
flattened ribs, which have their sides serrated, the interstices 
narrow, with a small serrated rib in the middle, and the margin 
toothed. 4,3,...44. Peru. 
P. Gissus. Lam. 53.—Sow. Th. f. 1,2,17,76.—Ostrea G. 
Lin, 1147.—D.) p..267.=B. 1.52128.0f, 8.2 Ch. J. 619,0,8— 
O. Princrpauis & Fragertum. Gmel.—P. Soversir. Guiding. 
Rounded, ventricose, with concentric and radiating striz ; the ears 
nearly equal, striated and obtuse ; excessively variable in colour- 
ing, being dull brown, bright red, delicately pink, mottled with 
brown, light blue variegated with patches of dark brown and 
touches of white and yellow, with eighteen rather rough ribs: the 
right valve rather the more ventricose. 14...143. Pmrerfic. Wi ee 
Philippi. p. 83.—Mont. p. 145.—Sow. Th. f. 141 to 6.—Ostrea 
Ole Lins 11464-D Alp 265:— War. Mow, AS dasha. 1m, 
S. 27.—E. t. 212. f. 2.—P. Picrus. Da. Cost. t. 9. f. 1,2,4, 5. 
Orbicular, rather ventricose, with concentric and radiating strie ; 
ears nearly equal, striated, obtuse, one in the lower valve rather 
the larger.and emarginated at the base; upper valve rough and 
more ventricose than the other, with eighteen to twenty subangu- 
lated ribs, with broad interstices; lower valve with the ribs less 
angulated and the interstices narrower; colour extremely variable, 
Ape tJ 
