Ostracodermi 
order of pleetognath fishes, represented only 
by the ostracionts or trunk-fishes, having the 
body covered with a solid coat of mail, no spi- 
nous dorsal fin, and teeth in the jaws. It con- 
tains only the family Ostraciontidee, thus con- 
trasted with the Selerodermi and the Gymno- 
dontes. See cut under cow-fish. 
OStracodermouS (os"tra-ko-der'mus), o. [As 
ostraeoderm + -0!ts.] Same as ostraeoderm. 
OStracodous (os'tra-ko-dus), fl. [As ostracode 
+ -oils."} Same &$ ostracode. 
Ostracopoda (os-tra-kop'o-da), n. pi. [NL., < 
Gr. oarpaKov, a shell, + n*f (wot)-) = E. foot.} 
An order of entomostracous crustaceans, re- 
lated to the Cladocera (Daphniacea) and Phyl- 
lopoda. It is characterized by a large, hard, and often 
calcified bivalve shell, or hinged shell-like valves, consist- 
ing of two unequal lateral parts of an unsymmetrical car- 
apace, movably joined together and often peculiarly orna- 
mented; arudimentaryabdomen; averysmallshell-gland; 
the body not ringed, ending in a bind tail; very few thora- 
cic appendages (generally two or three), not foliaceous, 
but cylindroid, like the legs of higher crustaceans ; bran- 
chiae attached to the oral appendages ; eyes, when present, 
median and coalesced or lateral and separate ; and anten- 
nules and antennee large and subserving locomotion. The 
Ostracopoda are mostly minute fresh-water crustaceans, 
swimming very actively by means of their antennae ; some 
carry their eggs about with them like ordinary Crustacea, 
but most attach them to foreign substances, as aquatic 
plants. These crustaceans are common in all geologic 
strata from the earlier Paleozoic formations, and appear 
to have undergone little modification. There are several 
families and a number of genera, such as Cypris and Cy- 
there. Also called Ostracoda and Ostrapoda. See cuts 
under Cypris and Cythereidce. 
Ostracostean (os-tra-kos'te-an), fl. and n, I. 
a. Pertaining to the Ostracosiei, or having their 
characters; placodenn. 
II. n. A fish of the group Ostracostei; a pla- 
coderm. 
Ostracostei (os-tra-kos'te-i), n.pl. [NL., pi. of 
ostracosteus : see ostracosteous. ] A group of ex- 
tinct placoganoid fishes having the head and 
generally the anterior part of the trunk incased 
in a strong armor composed of many large ga- 
noid plates immovably joined to one another. 
Also called Placodermata. 
ostracosteous (os-tra-kos'te-us), a. [< NL. os- 
tracosteus, < Gr. darpanov, a shell, + bartov, a 
bone.] Covered with shell-like plates of bone ; 
ostracostean ; placodermatous. 
ostralegus(os-tral'e-gus), n. [NL., irreg. < Gr. 
oorpeov (L. ostrea), an oyster, + Aeyeiv, pick out.] 
An old book-name of the oyster-catcher, now 
called Haimatopus ostralegus or ostrilegus. Also 
ostralega. 
Ostrapoda (os-trap'o-da), n. pi. Same as Os- 
tracopoda. 
Ostrea (os'tre-a), n. [NL., < L. ostrea, rarely 
ostreum, < Gr. "oarpe ov, an oyster: see oyster.'] 
The typical and leading 
genus of the oyster fam- 
ily, Ostreidce, having the 
shell inequilateral and 
inequivalve, with one 
valve flatter than the 
other. There are upward of 
200 species, besides many nat- 
ural and artificial varieties. 
The genus extends back to the 
Carboniferous, and there are 
more species extinct than ex- 
tant. The common edible 
oyster of Em-ope is 0. edutis; 
that of the Atlantic coast of 
the United States is 0. mrgin- 
ica. See also cuts under cibo- 
rium and integropalliate. 
ostreaceous (os-trf-a'shius), a. [< NL. *ostrea- 
ceus, < L. ostrea, an oyster: see Ostrea.'] Same 
as ostracean. 
This distinction of two Interior vehicles or tunicles of the 
soul, besides that outer vestment of the terrestrial body 
E* ed in Plato TO oo-Tpea8e?, the crustaceous or ostreaceous 
), is not a mere figment of the latter Platonists since 
stianity, but a tradition derived down from antiquity. 
Cudutorth, Intellectual System, p. 790. 
ostreiculture (os'tre-i-kul'tur), n. [Irreg. < L. 
ostrea, oyster, + cultura, "culture.] Oyster- 
culture ; the artificial breeding and cultivation 
of ousters. Also ostreacnlture. 
OStreiculturist (os"tre-i-kurtur-ist), n. [< os- 
treiculture + -ist.~\ One who cultivates oysters, 
or is engaged in the industry of propagating 
these bivalves. 
The theory of hybridation advocated by some ostreieid- 
turists. The American, V. 88. 
Ostreidae (os-tre'i-de), n.pl. [NL., < Ostrea + 
-idai.~\ A family of monomyarian bivalve mol- 
lusks, the oysters, typified by the genus Ostrea, 
to which various limits have been assigned. 
(a) In Woodward's and older systems, a large group in- 
cluding all forms with the mantle quite open, a very small 
4172 
foot or none, an inequivalve shell, free or adherent to for- 
eign bodies, resting on one valve, with central beaks, in- 
ternal ligament, single adductor muscle, and obscure pal- 
linl line. Thus it included not only the Ostreidce proper, 
but also Anomiidas, Placunidce, t'ectinidce, Limidoe, and 
SpondyKdas. (b) Now restricted to oysters which have the 
mantle-margin double and finely fringed, nearly equal gills 
united to one another behind, and the mantle lobes form- 
ing a complete branchial chamber. The shell is irregular, 
being both inequivalve and inequilateral, attached by the 
left valve, and the ligament-cavity is triangular or elon- 
gated. In structure the shell is subnacreous, and lami- 
nated with prismatic cellular substance. Thus limited, the 
Ostreidce contain only the oysters and closely related bi- 
valves, of which there are many species, extinct and extant. 
Pearl-oysters belong to a different though related family, 
AvimKdce. 
OStreiform (os'tre-i-f6rm), a. [< L. ostrea, an 
oyster, + forma! form.] Oyster-like; resem- 
bling an oyster in form ; ostraceous. 
OStreophagist (os-tre-of'a-jist), n. [< Gr. oa- 
rpeov, an oyster, + ipayElv, eat, + -ist.'] An oys- 
ter-eater; one who or that which eats or feeds 
upon oysters. 
ostrich (os'trich), n. [Formerly also ostridgc, 
austridge, estridge; < ME. ostriche, ostryche, 
ostrice, oystridhe, < OF. ostruche, ostruce, aus- 
truche, F. autruche = Pr. estruz = Sp. avestruz 
= Pg. abestrus, < LL. avis struthio(n-), also sim- 
ply struthio(n-) (the native word avis, bird, be- 
ing added to the foreign name of the bird), < 
Gr. arpovOiov, an ostrich, earlier arpovBoKd^of 
(> L. struthiocamelus for stnithio camelus or 
*struthocamelus), an ostrich, lit. 'camel-bird,' 
so called with ref . to its long neck, < arpoMs, a 
bird, esp. a sparrow ; cf . li fitya^ aTpov66f, lit. ' the 
great bird,' arpovS6( Kardyaiof, 'ground-bird,' 
arpov66s ^tpffatoc, 'land-bird,' crpov66^ A</3iof, 
' Libyan bird,' aTpov66f 'Apapiof, 'Arabian bird,' 
or simply arpov66f, all applied to the ostrich. 
From the LL. struthio are also AS. struta = 
OHG. MHG. struz, G. strausz; also, after MHG., 
MLG. strus = D. struts = Sw. struts = Dan. 
struds; also It. struzzo, dim. struzsolo, = OF. 
strucion (> ML. reflex strucio(ti-) and ME. stru- 
cioun), ostrich.] A very large ratite bird of the 
genus Struthio. The true or African ostrich (& came- 
A Jurassic Oyster (Ostrea 
fnarstii). 
Osyris 
eggs appear to be hatched mainly by incubation, both pa 
ren ts relieving each other in the task, but also partly by the 
heat of the sun. The South African ostrich is often consid- 
ered as a distinct species under the name of S. australis. 
Three South American birds of the genus Rhea are popu- 
larly known as the American ostrich, though they are not 
very closely allied to the true ostrich, differing in having 
three-toed feet and in many other respects. The best- 
known of the three is K. americana, the nandu or nan- 
duijiutfu of the Brazilians, inhabiting the great American 
pampas south of the equator. It is considerably smaller 
than the true ostrich, and its plumage is much inferior. 
K. darwini, a native of Patagonia, is still smaller, and be- 
longs to a different subgenus (Ptilocnemii). The third spe- 
cies is the R. macrorhyncha, so called from its long bill ; 
it is perhaps only a variety of the first. 
The daughter of my people is become cruel, like the os- 
triches in the wilderness. Lam. iv. 8. 
They ride on swift horses, . . . nor are they esteemed 
of if not of sufficient speed to overtake an Ostridge. 
Sandys, Travailes, p. 108. 
OStrich-board (os'trich-bord), n. In medieval 
arch., wainscot. 
ostrich-farm (os'trich-farm), n. A place where 
ostriches are kept and reared for the commer- 
cial value of their feathers. 
ostrich-farming (os'trich-far // ming), n. The 
occupation of Keeping and rearing ostriches 
for the sake of their feathers ; the conduct of 
an ostrich-farm. 
ostrich-feather (os'trich-feTH*'er), . One of 
the long curly plumes of the ostrich, used for 
ornamental purposes; an ostrich-plume. 
OStrich-fern (os'trich-fern), n. The fern Ono- 
clea Struthiopteris (Struthiopteris Germanica of 
earlier authors). See cut under Onoclea. 
OStrich-plume (os'trich-plom), n. 1. A plume 
of an ostrich;, an ostrich-feather; specifically, 
one of the quill-feathers of the wings or tail. 
2. A name of Aglaophenia struthionides, one of 
the plumularian hydromedusans. See Aglao- 
phenia. 
Ostridae (os'tri-de), n.pl. Same as Ostreidce. 
ostridget, An obsolete form of ostrich. 
ostriferous (os-trif'e-rus), a. [< L. ostrifer, 
oyster-bearing, < ostrea, oyster, + ferre = E. 
bear 1 .'] Bearing or producing oysters. 
Ostrogoth (os'tro-goth), n. [< LL. OstrogotM, 
pi., < OHG. ostar', east, + LL. Gothi, Goths: see 
Goth.] A person of the more easterly of the 
two great historical divisions of the Goths (see 
Goth). They established a monarchy in Italy 
in 493, which was overthrown in 555. Also called 
East Goth. 
Ostrogothic (os-tro-goth'ik), a. [< Ostrogoth + 
-ic.] Of or relating to the Ostrogoths. 
ostryt, . Same as hostry. 
Ostrya (os'tri-a), n. [NL. (Scopoli, 1772), < 
Gr. oarpva, also oarpvf, some tree with hard wood ; 
cf. darpaicov, a shell.] A genus of apetalous 
trees, the hop-hornbeams, of the order Cupuli- 
ferce, or oak family, and the tribe Corylece, known 
by the cone-like fruit of flattish-inflated mem- 
branaceous bracts inclosing small sessile bony 
nuts. There are 6 species, natives of the north temper- 
ate zone, in the Old World and North and Central Amer- 
ica. They bear alternate leaves and small catkins without 
A Male Ostrich (Stntthio camtltts). 
l-us) inhabits the sandy plains of Africa and Arabia, and 
is the largest of all existing birds, attaining a height of 
from 6 to 8 feet. The head and neck aje nearly naked, 
and the quill-feathers of the wings and tail have their barbs 
wholly disconnected. It is chiefly for these plumes, which 
are highly esteemed as articles of dress and decoration, that 
the bird is hunted and also reared in domestication. The 
legs are extremely strong, the thighs are naked, and the 
tarsi are covered with scales. There are only two toes, the 
nrst and second being wanting. The pubic bones are 
united a conformation occurring in no other bird. The 
wings are of small size and incapable of being used as 
organs of flight; the birds can run with extraordinary 
speed, distancing the fleetest horse. The food consists of 
grass, grain, and other substances of a vegetable nature. 
Ostriches are polygamous, every male consorting with sev- 
eral females, and they generally keep together in larger or 
smaller flocks. The eggs are of great size, averaging three 
pounds each in weight, and several hens often lay in the 
same nest, which is merely a hole scraped in the sand. The 
Branches of Hop-hornbeam (Ostrya vtrgt'nica). 
I, male, and 2, female inflorescence ; a. male flower; b, fruit. 
floral envelops, the tubular bracts in fruit becoming blad- 
dery sacs. See hop-hornbeam, ironwood, and leverwood. 
Oswego tea. See tea. 
Osyridese (os-i-rid'e-e), n. pi. [NL. (A. L. de 
Jussieu, 1802), < Osyris + -idea.] A tribe of 
plants, of the apetalous order Santalacea:, dis- 
tinguished by the coalescence of perianth-tube 
with the ovary or disk. It includes about 20 
genera, Osyris being the type. 
Osyris (os'i-ris), n. [NL. (Linnteus, 1737), < L. 
Hityris, < Gr. bavpif, a plant, identified by Spren- 
gel with Osyris alba, by others with lAnaria ritl- 
qaris; supposed to refer, like Gr. o<7<p'TW. an 
Egyptian plant, to the Egyptian god Osiris : see 
