27 
O S T 
public envy. His reputation was a fufficient reafon for 
his banifhment. Such was the cafe with Ariftides and 
fome others. See the article Greece, vol. viii. p. 856. 
OS'TRACITE, f. [from ojirea, Lat.] The common 
oyfter in its foflil ftate. Oftracites are of various fhapes 
and kinds ; and the name is by fome authors made to Sig¬ 
nify the (hell itfelf, when preferved in its native (late and 
condition, as is the cafe with thofe found about Wool¬ 
wich and Blackheath ; and by others, the Hones call or 
formed in thofe (hells, or in cavities from whence they 
have been waftied away and diflblved. In both thefe cafes 
the ftone carries the exadl refemblance of the (hell, even 
in its niceft lineaments; in the find cafe, bearing every 
mark of the infide, in the other, of the outer furface. 
We. have this ftone in great plenty in many parts of Eng¬ 
land ; and it is very famous, in fome places, for its vir¬ 
tues in cafes of the gravel, and the like complaints. Dr. 
Home, in the Phil. Tranf. fays, the oftracites rather 
diftolves the little (tones than forces them out, as not be¬ 
ing remarkably diuretic. He adds, that he prefcribes it 
in powder, with a third part of (lores chamsemeli. The 
' dole is from half a drachm to a whole one,.in white 
wine. 
It is to be obferved, that all the foflil (hells, and par¬ 
ticularly the lapides Judaici, or Jews’ (tones, which have 
been the fpines of fea echini, have been efteemed diure¬ 
tics, and good in the ftone and gravel. Among the an¬ 
cients, Diofcorides, Pliny, and all the reft, recommend 
them highly. 
Ostracites is alfo the name of a kind of cadmir, found 
at the bottom of furnaces where copper is purified. It 
is very heavy, and in ftrufture refembles an oyfter-(hell ; 
whence its name. It has been efteemed aftringent and 
deterfive; and introduced as an ingredient in feveral un¬ 
guents. 
OSTEAU', a town of Moravia, in the circle of Hra- 
difch, on an iilar.d in the river Marfch : feven miles fouth 
of Hradilch. 
OSTRAU', or Ostrow Ma'Hrisch, a town of Mora¬ 
via, in the circle of Prerau, on a river of the fame name, 
on the borders of Silefta: twenty miles' fouth-eaft of 
/ Troppau, and forty eaft-north-eaft of Prerau. Lat. 49.47. 
N. Ion. 18. 17. E. 
OSTRA'VA, or Os'trawice, 'a river which feparates 
the principality of Tefchen from Moravia, and runs into 
the Oder five miles fouth of Oderburg. 
OSTRE'A, j. The Oyster ; in natural hiftory, a genus 
of the clafs vermes, or worms, order teftacea. Generic 
characters-—-Animalatethys; (hell bivalve, generally with 
unequal valves, and (lightly eared ; hinge without teeth, 
but furnifhed with an ovate hollow, and moftly lateral 
tranfverfe grooves: thus they are immediately diftin- 
guifhed from the genus Area, in not having teeth alter¬ 
nately locking in each other. 
This genus comprehends the two ex ten five families of 
PeCtens or Scallops, and Oyfters ; and there are no lefs 
than a hundred and thirty-fix fpecies in the whole. In 
both diviiions, the animal is well known as a nutritive 
and valuable food. Both fcallpps and oyfters are found 
plentifully in the Indian Seas,-the Mediterranean, the 
American Ocean, and in the European feas, where they 
conftitute a confiderable article of commerce. The fcal- 
lops grow a fort of coarfe byfius ; and have the agility of 
leaping full half a yard out of the fea, at which time they 
open their (hells, and fpout out the dale water within 
them ; after which they rapidly fink, taking in frefh wa¬ 
ter, and clofing their (hells with a loud fnap, which be¬ 
trays their beds to the watchful fiftierman. 
The difference between the Oyfter and the Scallop is fo 
obvioufly impreffed by the hand of nature on the refpec- 
tive (hells which compofe them, that few writers on this 
fubjeft have paffed filently over the impropriety of thus 
placing them together. The Scallop differs from the oyf¬ 
ter in being endowed with a higher locomotive power : 
the animal is different in having the branchiae cirrhated, 
O S T 
or fringed ; in being furniihed with a kind of foot, like 
the Cardium echinatum, delineated in the Helmintho¬ 
logy Plate IV. fig. a. which it protrudes from the (hell 
near the auricle of the hinge; and in throwing out a 
byffus fimilar to the pinna and the mufcle, by which it 
fixes itfelf to other bodies. Ariftotle, and other ancient 
writers, attribute to the feallop the power of fpringing 
from place to place on the fea-fhore. Argenville deferibes 
its movements both in the water and out 5 he relates, 
that when left dry, by a fudden clofing of its valves, af- 
fifted by the foot, it has the power of fpringing four or 
five inches at a jerk, repeating this motion in order to 
regain its element. “ In the water, (he fays,) it has the 
power of rifing and fuftaining itfelf near the furface, 
turning about in various directions, and on any alarm 
fuddenly clofing the valves and finking to the bottom. 
The Oyfter, on the contrary, has the branchiae fimple, 
and not fringed, and is unfurni(hed either with a foot or 
with byfius ; and its powers of motion confift in turning 
either the flat or convex fide upwards or downwards; and 
even to efteCt this, the animal is faid to take advantage 
of the force of the ebbing or flowing of the water to afllft 
it.” Yet (till, in the articulation of the hinge, the gene¬ 
ric character holds good. 
I. Scallops. Valves furnifhed with ears, and radiate. 
1. Equilateral; ears of the valves equal. 
1. Oftrea maxima, the large peCten, or pilgrim’s feal¬ 
lop : (lie 11 with fourteen rounded longitudinally-ftriate 
rays. This is delineated by Mr. Donovan, in his Britiftx 
Shells. There are two other varieties deferibed by Lifter 
and Knorr: our reprefentation, at fig. 1. on the annexed 
Plate, is from the latter. Thefe are found in mod Eu¬ 
ropean teas, in large beds ; whence they are dredged up, 
apd pickled and barrelled for fale. This is the (hell that 
was formerly worn by pilgrims on the hat or coat, as a 
mark that they had croffed the fea, for the purpofe of 
paying their devotions in the Holy Land ; in commemo¬ 
ration of which it is ftill preferved in the arms of many 
families. The (hell is five or fix inches long, and rather 
broader; the ears are large, with deculfate Arise; the 
hinge with a large deep hollow ; lower valve convex, 
white, often varied with red bands or fpots; the upper 
valve is flat and reddidi. 
2. Oftrea Jacobaea : (hell with about fourteen angular 
and longitudinally-ftriate rays. It inhabits European 
feas. The grooves of the (hell are tranfverfely ftriate ; 
the upper valve is flat; the lower vidve with angular rays ; 
the ears are concave and fmooth on the upper fide. See 
fig- 2- . 
3. Oftrea ziczac: (hell with flattened rays. It inhabits 
the American Ocean ; fometimes of one colour, fome- 
times variegated ; the’ears are very finely wrinkled ; the 
lower valve is convex, with from eighteen to twenty rays, 
which are very finely ftriate tranfverfely, and about twice 
the number of perpendicular (trite within. The upper 
valve is flat. 
4. Oftrea ftriatula: (hell with fixteen faint rays and 
tranfverfe membranaceous Arise ; the margin very entire. 
It is found in the Indian Ocean. The (hell is middle- 
fized, varied with purple and white, within yellowi(h. 
5. Oftrea minuta: (hell with twenty convex rays. It 
inhabits the Indian Ocean. The (hell is about the fize 
of a nut: lower valve white, and very convex ; upper 
valve white clouded with brown, flatter and plaited. - 
6. Oftrea pleuroneftes : (hell equivalve, with twelve 
doubled rays, and fmooth on the outfide. It inhabits the 
Indian Ocean ; it is fometimes reddidi, or of a fle(h-co- 
lour, or liver-colour ; within it is filVery. There is a va¬ 
riety of an orange-colour radiate with red ; it is four 
inches and a half long, and gaping at each end. 
7. Oftrea Laurentii : upper valve fub-convex, fmooth, 
with fine perpendicular lines crofting very fine concentric 
tranfverfe Arise; lower valve with twenty-four rays and 
forty- 
