O S T 
lower valve. It inhabits the African feas ; is ovate, mi¬ 
nute, pellucid, glabrous, white ; the upper valve fpotted 
with red. 
47. Oftrea obliterata : {hell fmooth on the outfide, with 
twenty-four doubled rays. It inhabits the Indian Ocean. 
The (hell is marked with very fine decufl'ate ftriae ; the 
lower valve pale-reddilh, and yellowilh at the hinge ; up¬ 
per valve dirty-red, or pale-tawny. See the annexed Plate, 
%• 5 - 
48. Oftrea fanguinea: (hell equivalve, with twenty- 
two rough rays ; the ears are (mail. It inhabits the Me¬ 
diterranean, Atlantic, and American, feas. The (hell is 
round and flattifh, red, fcarlet, or tawny 5 the fpaces be¬ 
tween the rays are longitudinally ftriate, 
49. Oftrea varia-s (hell equivalve, with thirty com- 
prefled rays befet with tranfverfe prickly fcales; one ear 
very fmall. It is found in mod European feas; varies 
very much in colour, from pale-yellow to various (hades 
of orange and brown, with fometimes a few white fpots. 
The (hell is rather convex, with rough jags or fpinous 
protuberances down the rays; fpaces between the rays 
not ftriate ; one ear very fmall, with a double row of 
(pines ; the other with wrinkled plaits, and armed be¬ 
neath with from five to feven fpir.es. See fig. 6, 7. 
50. Oftrea pufio : (hell equivalve, with about forty fili¬ 
form rays, the furface often irregular or diftorted. It is 
found in the European, Atlantic, and American, feas. 
The (hell is generally fmall, and a little longer than it is 
broad; fometimes it is feen with a fmooth furface, but 
moftly with an irregular-waved furface, as if deformed by 
an accident. In its colours and marks it is very variable, 
but commonly of a fine red ; one of the ears is very 
fmall, the other (liarply fpined beneath. 
51. Oftrea obfoleta: (hell fmooth, equivalve, femi- 
tranlparent, dark-purple, with eight nearly-obfolete rays. 
Inhabits Britifti coafts; three quarters of an inch long. 
Shell thin, the valves equal and (hallow, within fmooth 
and brown, with a pearly glofs; outfide dull purplifti- 
brown, with numerous longitudinal ftriae between the 
rays ; ears very unequal, wrinkled. A fmall fpecies ; fee 
fig. 8. 
52. Oftrea laevis : (hell very fmooth ; ears ribbed. In¬ 
habits Anglelea and Falmouth ; is more than half an 
inch long. 
53. Oftrea glabra : ears nearly or quite equal. Shell 
equivalve, with from ten to fifteen fmooth flattifti rays ; 
the infide with elevated double ftriae. It inhabits the 
European and American feas ; nearly two inches long, 
and as many broad ; roundifh ; red, yellow, or brown, 
fpotted or clouded, fometimes white, with the upper valve 
fpotted with brown ; margin repand. 
54. Oftrea opercularis : (hell with about twenty rays, 
roundilh, and rough, with decufl'ate ftriae ; the upper valve 
a little more convex. It inhabits the northern feas of 
Europe ; and is two inches and a half long and broad. 
The (hell is gaping, generally variegated with fpots and 
other marks; rays acute, fometimes rounded; margin 
repand and toothed within ; ears with decufl'ate wrinkled 
ftriae, the larger one emarginate and fpinous under the 
incifure. In Devonlhire and Cornwall, where it is found, 
it is called frill or queen. 
55. Oftrea gibba: lliell equivalve, gibbous, with 
twenty glabrous rays. It inhabits the American and 
Atlantic feas. The (hell is convex on each fide, red, 
with fometimes a few white fpots, and marked with fine 
crenate longitudinal ftriae ; margin crenate ; ears nearly 
equal. 
56. Oftrea fulcata : (hell white, with flefli-colour fpots; 
the rays glabrous, thirty-two on the lower valve, and 
tw-enty-five on the upper. It inhabits the (liores of Ma¬ 
labar ; is about one inch and a half long, and fomething 
broader; margin plaited, crenate; lower valve with an 
emarginate fpinous ear, upper valve flattened. 
57. Oftrea hiftrionicat (hell thin, flattened, pellucid, 
”Vol. XVIII, No. 1221. 
REA. 1 29 
with very fine tranfverfe wrinkles, and eleven rays. The 
(hell is fpotted with red, white, and black ; rays waved ; 
ears nearly equal. 
58. Oftrea iflandica: (hell orbicular, with purple circles, 
and about one hundred rays. It inhabits the Mediterra¬ 
nean, in innumerable varieties. The (hell is three inches 
and a half long, and three inches and a quarter broad ; 
fometimes whitifh, but moftly mixed with a fine pale- 
bloom or yellowilh, and marked with tranfverfe femilunar 
bands ; upper valve more elegantly marked, with from 
fifty to one hundred rays, rough, with acute imbricate 
fcales; margin crenate ; ears with tranfverfe fcaly ftrise, 
the large one emarginate and fpinous : the fifh is eaten. 
This beautiful fpecies is reprefented at fig. 9. from Knorr. 
59. Oftrea triradiata : (hell nearly equivalve, glabrous, 
immaculate, with very minute ftriae. It is found among 
fuci in the feas of Norway. The (hell is red, with fmall 
white fpots, within reddifti ; upper valve with three rays ; 
ovary of the fifh yellowifli. 
60. Oftrea fuci: (hell nearly equivalve, ftriate, fpotted, 
rough towards the margin. It inhabits the North Seas, 
on the Fucus faccharinus. The (hell is rufous, with 
whitifti or paler fpots; within red, and quite fmooth, with 
pellucid fpots; rays of the upper valve obfolete ; ovary of 
the fi(h rich red. See the article Helminthology, 
Plate IV. figs. 8, 9. vol. ix. 
61. Oftrea tigerina : (hell nearly equivalve, ftriate, gla¬ 
brous, red with whitilh fpots. It inhabits the North Seas, 
on fuci. Lower valve more deeply grooved, and varied 
with large undulate confluent pale-yellow fpots ; upper 
valve dotted ; ovary of the fifti white, 
62. Oftrea feptem-radiata : (hell nearly equivalve, ftri¬ 
ate, glabrous, wdth feven convex rays. It inhabits the 
Northern Seas. 
63. Oftrea arata : (hell nearly equivalve, within and 
without grooved and red ; one part rough, the other 
glabrous. It inhabits the North Sea. 
64. Oftrea fenatoria : (hell convex each fide, with 
twenty-two rounded and tranfverfe wrinkled rays, the 
interftices with longitudinal granulate ftriae. It inhabits 
the Indian Ocean ; two inches nine lines long, and about 
as much broad , outfide chefnut varied with violet and 
white ; infide violet, the circumference bordered with 
dull-bay. 
65. Oftrea citrina: (hell orange, with twenty-two 
rounded rays and plaited margin ; lower valve flatter. It 
inhabits India ; fome of the rays are lcaly, and fome of 
the grooves have granulate lines. 
66. Oftrea turgida: (hell equally convex, both fid^s 
with twenty glabrous rays, the interftices with tranfverfe 
crowded wrinkles ; the margin with plaited teeth. It is 
found in the American and Indian Seas. 
67. Oftrea fulphurea : (hell flattened, thin, pellucid, 
ftriate, with numerous imbricate rays ; the margin with 
crenate plaits. It inhabits the Red Sea ; is two inches 
long, and a little narrower. The (hell is thin, fragile, of 
a fulphuror orange colour, fometimes red with an orange 
hinge and a (emiliinar white band, or varied with white 
and pale tawny, with a languineous border; lower valve 
with equal rays, thofe of the upper valve alternately lets. 
68. Oftrea porphyrea: (hell convex, purple, within 
white or red, with twenty-five thick rounded fcaly rays. 
It is found in the Red Sea; two inches three lines long, 
and as much broad ; (hell varied with a few white (pots. 
69. Oftrea vitrea : (hell hyaline, with an acute margin, 
very (lender rays, and concentric fcaly curves. It is found 
in the North Seas, among fuci and zoophytes ; fize of a 
pea ; (hell fmooth, brittle, white, or varied with white 
and red; one ear emarginate and fpinous. 
70. Oftrea Tranquebaria : (hell with twenty rounded 
rays, the interftices very finely wrinkled; margin repand. 
It inhabits Tranquebar ; fometimes of one colour, which 
is moftly orange 5 fometimes varied with undulate browrn, 
red, or cinereous, fpots; upper valve more convex. 
I 71. 
