OST 
others, the ftones caft or formed in thofe fhells, or in cavi- 
ties from wheuce they have been wafhed away and diffolved : 
in both thefe cafes the ftone carries the exact refemblance of 
It is to be obferved that all the foffile fhells, and particu- 
larly the ei Judaici, or Jew’s ftones, which have been 
the {pines of fea echini, hae eae iene: diuretics, and 
good in the flone and gravel. the ancients, Diofco- 
rides, ee and all the reft, = ommend them highly. 
Dr. , inthe Philof. Tranf. fays, the oftracites rather 
diffolves de Little ftones than forces them out, as not being re- 
markably diuretic. He adds, that he a . itin powder, 
with a third part of flores chamemeli. The dofeis from half 
a drachm to a whole one, in white 
Ostracites is alfo the name of a eer of cadmia, found 
at the bottom of furnaces where copper is purified. It is 
very heavy, and in ftru€ture refembles an oyfter-fhell ; 
whence its name. 
It has been efteemed aftringent and deterfive ; and in- 
troduced as an ingredient in feveral unguents. 
OSTRACODERMATA, a term ufed by Ariftotle to 
exprefs that clafs of fhells which we call ze — in woh 
fition to the cruftaceous animals, or malacoftra he 
finition Ariftotle gives of this clafs of animals Pa that deg 
are foft within, but hard without; that their fhells may be 
bruifed or broken, ite their parts cannot be torn from one 
another, as they can in the cruftaceous kind, ica as the 
lobfter ; whofe fhell — the legs, body, t awe be- 
diftin& pieces of thell, and ae 
be torn cade by pulling till ee mem- 
branes give way. Phi ranf. N° 219. p. 199. 
OS TRAU, or Ostrow Malrith in Geography, a town 
of Moravia, inthe circle of au, on ariver of the fame 
name, on the borders of Shae 3 20 miles 5.E. of Troppau. 
N. me 49° Ey ae atl 
RAU, a town ot Moe avia, in the circle of Hra- 
difch, on an ifland in the river Marfch; 7 miles S. of 
Hradifch. 
OSTRAVA, or Osrrawiec, a river which feparates 
the principality of Tefchen from Moravia, and runs into the 
Oder, 5 milesS. of Oderburg. 
REA, the oo in Natural Hifory, a genus of 
the clafs and order Verm ftacea. Animal a tethys; 
fhell tae generally a unequal valves, and flightly 
without teeth, but deal — an ovate 
OF this 
‘Set ion 
nifhed eile ears and radiate; Agaarinted Scallop. Thefe 
leap out of the water to the diftance of half a yard, and 
opening the fhells, eje&t the water within them; after which 
they fink under water, and fuddenly clofe the fhells with a 
ng fnap. This feGion is fubdivided into three fubfeétions, 
(a) equilateral; ears of the valves equal, containing 
forty {pecies: (6) ears unequal, one of them generally ciliate 
with {pines within, containing fifty- (c) valves 
more gibbous on one fide; in this fubfection there are feven 
fpecies. 5 
four fF pec ies: and 
OST 
a. Equilateral; ears of the valves equal. 
Species. 
* MAXIMA. as with fourteen rounded longitudinally 
i hi 
ftriate rays is delineated b Donov. i 
Britifh Shells ae are two other varieti.s defcribed by 
Thefe are found moit European feas, 
in large beds; whence they are dredged up, and pickled 
and barrelled for fale. This is the fhell that was formerly 
worn by pilgrims on the hat or coat, as a mark that they 
had croffed the fea, for the purpofe cE paying their devo- 
tions in the Holy Land, in commemoration of which it is 
{till-preferved in the arms of many families. The fhell ia 
five or fix inches long, and rather broader; the ears are 
large, with decuflate ftrie; the hinge with a large ne 
hollow ; lower valve convex, white, often varied with r 
bands or fpots; the upper valve is flat and reddifh. 
* Jacop£ZA. Shell with about fourteen angular and lon- 
gitudinally ftriate rays. 
lefs than the la 
; valve with an- 
gular rays; the ears are concave and fmovth on the upper 
fide. 
Ziczac. Shell with uence rays. It inhabits the 
American ocean ; fometimes of one colour, fometimes varie- 
gated; the ears are very finely cried: ; the lower valve is 
convex, with from eighteen tou.twenty rays, which are very 
finely ftriate tranfverlely, and about twice the number of 
perpendicular itriz within. ‘The upper valve is flat. 
S La. Shell with fixteen faint sk with tranfverfe 
membranaceous frie; the margin very e It is found 
inthe Indian ocean. The fhell is middle- ‘ized, varied vith 
purple and white, within yellowifh. 
A. Shell with twenty convex rays. It pa 
e Indian ocean. The fhell is about the fize of a nu 
is valve white and very convex; upper valve ee 
clouded with brown, flatter and plai 
PL N Shell equivalve, with twelve doubled 
t its the Indian 
colour ; within it is filvery. There is a variety of an orange- 
colour nade with red; it is four inches and a half long, 
valve fub-convex, fmooth, with 
long, and about as broad 
JAFonicA. Shell equivalve, a little convex, margined 
with yellow ; upper valve with faint lines croffing concentric 
tran{verfe bands, and forty elevated ftriz within. It is 
found on the fhores of Guinea and Japan ; is about five 
inches and a half long and ed retembles the O. 
a pa but is ela and t 
MAGELLANICA. ell of ne 18  likewife equivalve, 
ius with oblong crowded ftriz ound in the 
{traits of Magellan 5 it eeltaoies the ‘0. ceuouedes he 
ell is lateritious, not radiate, quite {mooth within; upper 
valve more convex ; lower valve flatter than in moft others, 
the ears are tran{verfely ftriate. 
Hysripa. Shell with nine or ten rays, the interftices 
longitudinally ftriate; margin repand within. It inhabits 
e Norwa 3 thin, lover valve — upper valve fan- 
guineous, -_ angular veins and line 
Rap Sheil nearly equal, an twelve convex 
hays crofied by crenate ftrie. is found in the - ndian 
ean 5 
a 
4 
