Ptenoglossa
Pte•no•glos´sa, n. pl. [NL., fr. Gr. feathered + tongue.] (Zoöl.) A division of gastropod mollusks having the teeth of the radula arranged in long transverse rows, somewhat like the barbs of a feather.

Ptenoglossate
Pte•no•glos´sate, a. (Zoöl.) Of or pertaining to the Ptenoglossa.

Pteranodon
Pte•ran´o•don, n. [Gr. wing + priv. +,, a tooth.] (Paleon.) A genus of American Cretaceous pterodactyls destitute of teeth. Several species are known, some of which had an expanse of wings of twenty feet or more.

Pteranodontia
Pte•ran•o•don´ti•a, n. pl. [NL.] (Paleon.) A group of pterodactyls destitute of teeth, as in the genus Pteranodon.

Pterichthys
Pte•rich´thys, n. [NL., fr. Gr. wing + fish.] (Paleon.) A genus of Devonian fossil fishes with winglike appendages. The head and most of the body were covered with large bony plates. See Placodermi.

Pteridology
Pter•i•dol´o•gy, n. [Gr.,, a fern + -logy.] That department of botany which treats of ferns.

Pteridomania
Pter•i•do•ma´ni•a, n. [Gr.,, a fern + E. mania.] A madness, craze, or strong fancy, for ferns. [R.] C. Kingsley.

Pteridophyta
Pter•i•doph´y•ta, n. pl. [NL., from Gr.,, a fern + a plant.] (Bot.) A class of flowerless plants, embracing ferns, horsetails, club mosses, quillworts, and other like plants. See the Note under Cryptogamia. — Pter´i•do•phyte• (#), n. This is a modern term, devised to replace the older ones acrogens and vascular Cryptogamia.

Pterocletes
Pter•o•cle´tes, n. pl. [NL., fr Pterocles, the typical genus, fr. Gr. feather +,, a key, tongue of a clasp.] (Zoöl.) A division of birds including the sand grouse. They are in some respects intermediate between the pigeons and true grouse. Called also Pteroclomorphae.

Pterodactyl
Pter•o•dac´tyl, n. [Gr. a wing + finger, toe: cf. F. pterodactyle.] (Paleon.) An extinct flying reptile; one of the Pterosauria. See Illustration in Appendix.

Pterodactyli
Pter•o•dac´ty•li, n. pl. [NL.] (Paleon.) Same as Pterosauria.

Pteron
Pte´ron, n. [NL., fr. Gr. a wing.] (Anat.) The region of the skull, in the temporal fossa back of the orbit, where the great wing of the sphenoid, the temporal, the parietal, and the frontal hones approach each other.

Pteropappi
Pter•o•pap´pi, n. pl. [NL., from Gr. a feather, a bird + a grandfather.] (Zool.) Same as Odontotormae.

Pteropoda
Pte•rop´o•da, n. pl. [NL.] (Zoöl.) A class of Mollusca in which the anterior lobes of the foot are developed in the form of broad, thin, winglike organs, with which they swim at near the surface of the sea. The Pteropoda are divided into two orders: Cymnosomata, which have the body entirely naked and the head distinct from the wings; and Thecosomata, which have a delicate transparent shell of various forms, and the head not distinct from the wings.

Pteropodous
Pte•rop´o•dous, a. (Zoöl.) Of or pertaining to the Pteropoda.

Pterosaur
Pter´o•saur, n. [Gr. wind + a lizard.] (Paleon.) A pterodactyl.

Pterosauria
Pter•o•sau´ri•a, n. pl. [NL.] (Paleon.) An extinct order of flying reptiles of the Mesozoic age; the pterodactyls; — called also Pterodactyli, and Ornithosauria. The wings were formed, like those of bats, by a leathery expansion of the skin, principally supported by the greatly enlarged outer or " little" fingers of the hands. The American Cretaceous pterodactyls had no teeth. See Pteranodontia, and Pterodactyl.

Pterostigma
Pter•o•stig´ma, n. ; pl. Pterostigmata (#). [NL., fr. Gr. wing +,, a mark.] (Zoöl.) A thickened opaque spot on the wings of certain insects.

Pterotic
Pte•ro´tic, a. [Gr. wing +,, ear.] (Anat.) Of or pertaining to, or designating, a bone between the proötic and epiotic in the dorsal and outer part of the periotic capsule of many fishes. — n. The pterotic bone. The pterotic bone is so called because fancied in some cases to resemble in form a bird’s wing

Pterygium
Pte•ryg´i•um, n. ; pl. E. Pterygiums (#), L. Pterygia (#). [NL., fr. Gr., properly a dim, akin to a feather.] (Med.) A superficial growth of vascular tissue radiating in a fanlike manner from the cornea over the surface of the eye.

Pterygoid
Pter´y•goid, a. [Gr.,, a wing + -oid.] (Anat.) (a) Like a bird’s wing in form; as a pterygoid bone. (b) Of, pertaining to, or in the region of, the pterygoid bones, pterygoid processes, or the whole sphenoid bone. — n. A pterygoid bone. Pterygoid bone (Anat.), a bone which corresponds to the inner plate of the pterygoid process of the human skull, but which, in all vertebrates below mammals, is not connected with the posterior nares, but serves to connect the palatine bones with the point of suspension of the lower jaw. — Pterygoid process (Anat.), a process projecting downward from either side of the sphenoid bone, in man divided into two plates, an inner and an outer. The posterior nares pass through the space, called the pterygoid fossa, between the processes.

Pterygomaxillary
Pter•y•go•max´il•la•ry, a. [ Pterygoid + maxillary.] (Anat.) Of or pertaining to the inner pterygoid plate, or pterygoid bone, and the lower jaw.

Pterygopalatine
Pter•y•go•pal´a•tine, a. [ Pterygoid + palatine.] (Anat.) Of or pertaining to the pterygoid processes and the palatine bones.

Pterygopodium
Pter•y•go•po´di•um, n. ; pl. Pterygopodia (#). [NL., fr. Gr.,, a fin +, dim. of,, a foot.] (Anat.) A specially modified part of the ventral fin in male elasmobranchs, which serves as a copulatory organ, or clasper.

Pterygoquadrate
Pter•y•go•quad´rate, a. [ Pterygoid + quadrate.] (Anat.) Of, pertaining to, or representing the pterygoid and quadrate bones or cartilages.

Pteryla
Pte•ry´la, n. ; pl. Pterylae (#). [NL., fr. Gr. feather + wood, forest.] (Zoöl.) One of the definite areas of the skin of a bird on which feathers grow; — contrasted with apteria.

Pterylography
Pter•y•log´ra•phy, n. [ Pteryla + -graphy.] (Zoöl.) The study or description of the arrangement of feathers, or of the pterylae, of birds.

Pterylosis
Pter•y•lo´sis, n. [NL., fr. NL. & E. pteryla.] (Zoöl.) The arrangement of feathers in definite areas.

Ptilocerque
Ptil´o•cerque, n. [Gr. a feather + tail.] (Zool.) The pentail.

Ptilopaedes
Ptil•o•pae´des, n. pl. [NL., fr. Gr. a feather +,, offspring.] (Zoöl.) Same as Dasypaedes.

Ptilopteri
Pti•lop´te•ri, n. pl. [NL., fr. Gr. a downy feather + wing.] (Zoöl.) An order of birds including only the penguins.

Ptilosis
Pti•lo´sis, n. [NL., fr. Gr a feather.] (Zoöl.) Same as Pterylosis.

Ptolemaic
Ptol•e•ma´ic, a. Of or pertaining to Ptolemy, the geographer and astronomer. Ptolemaic system (Astron.), the system maintained by Ptolemy, who supposed the earth to be fixed in the center of the universe, with the sun and stars revolving around it. This theory was received for ages, until superseded by the Copernican system.

Ptolemaist
Ptol´e•ma•ist, n. One who accepts the astronomical system of Ptolemy.

Ptomaine
Pto´ma•ine, n. [From Gr. a dead body.] (Physiol. Chem.) One of a class of animal bases or alkaloids formed in the putrefaction of various kinds of albuminous matter, and closely related to the vegetable alkaloids; a cadaveric poison. The ptomaines, as a class, have their origin in dead matter, by which they are to be distinguished from the leucomaines.

Ptosis
Pto´sis, n. [NL., fr. Gr. a falling.] (Med.) Drooping of the upper eyelid, produced by paralysis of its levator muscle.

Ptyalin
Pty´a•lin, n. [Gr. spittle. See Ptyalism.] (Physiol. Chem.) An unorganized amylolytic ferment, on enzyme, present in human mixed saliva and in the saliva of some animals.

Ptyalogogue
Pty•al´o•gogue, n. [Gr. spittle + driving.] (Med.) A ptysmagogue.

Ptysmagogue
Ptys´ma•gogue, n. [Gr. spittle + driving: cf. F. ptysmagogue.] (Med.) A medicine that promotes the discharge of saliva.

Ptyxis
Ptyx´is, n. [NL., fr. Gr. a folding.] (Bot.) The way in which a leaf is sometimes folded in the bud.