TESTACEOUS MOLLUSCA. 279 
oblquely plicated; ribs ten, thick, broad, with parallel nodo- 
sities, internally with tooth-like plaits. 215...14%. 4 smaller 
shell than Nodosus, with the ribs equal and the knobs less con- 
siderable. 
P. Maeniricus. Sow. Zool. Pr. 1835.—Sow. Th. f. 114. Sub- 
equivalve, equilateral, bright red, auricles unequal, with small very 
crowded radiating strie, and thirteen radiating ribs which are thick- 
ish rounded sometimes subnodose ; inside white with a purple 
margin. 54...54. E#. Columbia. 
P.Susnovosus. Sow Z. P. 1835.—Sow. Th. f. 97,112. Sub- 
equivalve, equilateral, the ears unequal, with very crowded radiating 
striz, and ten thick rounded radiating ribs, which are alternately 
subnodulous, or armed with bladder-like knobs ; inside usually 
stained with purple. 5}...5. Californian, Var. | Brownish red 
with white striee. Columbian Var. . Variegated with brown and 
white patches. Mewican Var. Bright orange, more depressed. 
Probably a variety of Nodosus. 
P. Noposus. Lam. 27.—Sow. Th. f. 115 and 147,—Ostrea. 
N. Lin. 1145.—D. p. 254.—W. t. 10 f. 18.—Rump. t. 48. f. 8. 
—P.Coratunvs. Ch. f.609.—Arg. t. 27, F. Orbicular, ventri- 
cose, reddish brown or bright orange, subequilateral, equivalve, 
with radiating sulci; ears unequal, sulcated, the posterior the larger, 
emarginated at the base ; hinge plicated ; the nine thick ribs armed 
with hollow round knobs, alternately smaller, internally in pairs, 
toothed atthe margin. 51...5. Braziland Isle of France. 
P. Muscosus. Wood Sup. t. 2. f. 2. Subquadrate, extremely 
ventricose, equilateral, equivalve, reddish brown, scabrous; ears 
unequal, elongated-acute, with scabrous sulci, notched at the base, 
the posterior the longer: umbones prominent; the eighteen sca- 
brous and subangulated ribs armed with short straight spines at the 
angle, and toothed at the margin. 14...1,% 
10 
P. Rucosus. Sow. Jun. Z. P. 1842.—Sow. Th. f. 226. Oval, 
ventricose, thick, scabrous, equivalve, subequilateral, paie yellow- 
ish, obscurely mottled with smoky brown, with twenty elevated ribs 
armed with numerous small annulated scales, their edges serrated, 
and their interstices smooth: ears unequal, with scabrous sulci, 
the anterior the smaller, the posterior notched at the base. 12 
.--14. Philippines. 
P. Pes Fetts. Lam. 29.—Son. Th. f. 162 and 234.—Reeve. t, 
114. f.4.—Philippi. p. 84. Osrrea P. Gmel. 3323.—W. t. 
10. f. 19.—D. p. 255,—Ch. f. 612,3.--O. Bornu. Pay. p. 76.— 
O.Enoneata. Born. t. 6. f. 2. ?—O. Coraruina, Poli 2. t. 28. 
f-. 16. Oval subtriangular, compressed, scabrous, with radiating 
sulci, equivalye, subequilateral, thick, reddish brown variegated 
