PRESTER´NUM, _n._ Anterior segment of the breast-bone.
PRI´MARY, _n._; pl. _primaries_. Any one of the (usually ten, often
nine, rarely eleven) large stiff quills growing upon the pinion or
hand-bone, as distinguished from the secondaries which grow upon the
forearm. They form the tip of the wing, and much of its surface.
PRI´MARY WING-COVERTS, _n. pl._ Those overlying the bases of the
primaries.
PROCE´RES or PRO´CERI, _n. pl._ Same as RATITÆ (which see).
PROLIG´EROUS, _a._ See YOLK.
PRONA´TION, _n._ A particular movement of the radius upon the ulna, by
which the hand turns over,—in birds it is very slight, if it occur at
all. The reverse movement is termed _supination_. The muscles effecting
it are _pronators_ and _supinators_.
PROÖT´IC, _a._ for _n._ An element of the auditory capsule.
PROSENCEPH´ALON, _n._ A certain tract of the brain, the third from
behind.
PRO´TOPLASM, _n._ Primitive common embryonic tissue, out of which
different organs and parts are formed.
PROTOVER´TEBRÆ, _n. pl._ First trace of the backbones.
PROTRAC´TILE, PROTRU´SILE, _a._ Susceptible of being thrust forward or
out, as the tongue of most woodpeckers.
PROVENTRIC´ULUS, _n._ Part of gullet, usually enlarged, next to gizzard,
having solvent glands for digestion. It is the true _stomach_ of a bird,
as distinguished from the gizzard or grinding stomach.
PROX´IMAL, _a._ Proximate; nearest or next to any centre or axis.
Opposed to _distal_ or _terminal_.
PSILOPÆ´DES, _n. pl._ A group of psilopædic birds, further distinguished
by being born weak and helpless, fed and reared in the nest. The term
_gymnopædes_ is synonymous.
PSILOPÆ´DIC, _a._ Having down growing only from the future pterylæ, as
the precursor of the future plumage, to which it is subsequently affixed
for a while and then falls off.
PSO´AS, _n._ Name of certain pelvic muscles.
PTERAPOPH´YSIS, _n._ Certain process of cranial bones.