Part 164

OS, n.; gen. ossis; pl. ossa. Bone. Many or most names of individual bones are adjectives, used substantively, os or bone being understood; as, hyoid or hyoides, hyoid (bone) or (os) hyoides, etc. The quadrate bone or os quadratum is, as to its physical characters and office, not found in animals above birds; it hinges the lower jaw, pterygoid, and malar bones to the rest of the skull. It is regarded as the homologue of the mammalian incus by some, by others as probably homologous with the mammalian malleus.

OS´CINE, a. Musical; capable of singing.

OS´CINES, n. pl. A group of singing-birds, possessing a complex vocal organ of numerous syringeal muscles, conferring musical ability. These are regarded as the highest or most perfectly developed of their class.

OS´SEOUS, a. Bony.

OS´SICLE, n. A small bone.

OSSIF´IC, a. Bony; rather, having power to ossify.

OS´SIFIED, a. Become bony; united by bone.

OS´SIFY. To form bone; to change into bone.

OSTEOLOG´ICAL, a. Pertaining to osteology.

OSTEOL´OGY, n. A description of bones. Also used to denote the osseous system, as myology, neurology, splanchnology, likewise are for their respective systems.

OS´TIUM, n. Doorway; entrance.

O´TIC, a. Pertaining to the ear.

O´TOCRANE, n. “Skull of the ear”; cavity containing essential organs of hearing.

OUTER COVERING. (142.) See INDUMENTUM and PTILOSIS.

OUTER WEB (of a feather). (150.) See POGONIUM EXTERNUM.

O´VAL, O´VATE, O´VOID, OVOID´AL, a. Egg-shaped; in a general sense, oblong and curvilinear. Distinctions which may subsist between these words are practically ignored among oölogical writers, who use them interchangeably for the oblong curvilinear shape when the curve is unequal at the opposite ends; the terms elliptical, ellipsoidal, being generally used to denote a curve equal at both ends. The transverse contour-line of an egg being always circular, the descriptive terms refer to the lengthwise contour, considered either as of a surface or a solid.

OVA´RIUM, n.; pl. ovaria, O´VARY, n.; pl. ovaries, Organ or tissue in which eggs originate; they subsequently acquire albuminous deposit, and, in birds, a calcareous shell, in the oviduct.

O´VIDUCT, n. Tube conveying eggs from ovary to cloaca.

OVIP´AROUS, a. Producing eggs which are developed after exclusion from the body. Opposed to viviparous.

OVIPOSI´TION, n. Act of laying eggs.

O´VISAC, n. Ovarian cavity in which an egg originates. Graafian vesicle.

OVULA´TION, n. Formation of eggs in, and discharge from, the ovary.

O´VUM, n.; pl. ova. Egg. Sometimes synonymous with embryo.

PAB´ULUM, n. Food; nourishment; aliment.

PADS. (123.) See TYLARI.

PALÆARC´TIC, a. Indigenous to the northern parts of the Eastern Hemisphere.

PALÆOGÆ´AN, a. Indigenous to the Eastern Hemisphere, or “Old World.”

PALÆORNITHOL´OGY, n. Science of fossil birds.