Part 64

DOWN, _n._ Small soft feathers of plumulaceous structure, generally growing about the roots of _plumæ_, and concealed by them. See PLUMULÆ.

DOWN´Y, _a._ Of plumulaceous structure. A part of the plumage is of down-feathers, and the bases of the contour feathers usually also are of _downy_ structure.

DUCT, _a._. Any tube for conveyance of an animal product; as _oviduct_, sperm-_duct_, lachrymal _duct_.

DUOD´ENAL, _a._ Pertaining to the duodenum.

DUOD´ENUM, _n._ A short portion of the upper intestine next to the gizzard, receiving the pancreatic and hepatic secretions.

DU´RA MA´TER, _n._ Outer membranous investment of the brain.

DUSK´Y, _a._ Of any undefined dark color.

E.

EARED, _a._ Having lengthened or highly colored auricular or other feathers on the side of the head. _Eared_ grebe; long-_eared_ owl.

EC´DYSIS, _n._ Moult; the shedding and renewal of plumage.

ECON´OMY (also written _œconomy_), _n._ Physical or physiological disposition. (Literally, regulation of a household.)

ECTO- (_in composition_). Outer.

ECTOZO´ÖN, _n._ External parasite, as a louse; same as _epizoön_. Opposed to _entozoön_.

EDEN´TATE, EDEN´TULOUS, _a._ Toothless, as nearly all birds are.

EDGE OF WING. (95.) See CAMPTERIUM.

EF´FERENT, _a._ Conveying outward or away; opposed to _afferent_.

EL´EMENT, _n._ A simple ultimate constituent part of a compound organ. The centrum is an _element_ of a vertebra.

EL´EVATED, _a._ Said of the hind toe when inserted above the level of the others.

ELON´GATE, _a._ Lengthened beyond usual ratio.

EMAR´GINATE, _a._ Notched at the end; slightly forked, especially in case of a tail so shaped; also notched, or abruptly narrowed along the edge, in its continuity, as the border of many a wing-quill.

EMBONPOINT, _n._ State of perfect health, as indicated by condition of fatness not amounting to corpulence or obesity.

EM´BRYO, _n._ Fecundated germ or rudiment of an animal; said of a bird until hatched, and therefore corresponding to _fœtus_ in mammalogy.

EMBRYOL´OGY, _n._ Science or study of the development of animals before birth or hatching.

EMBRYON´IC, _a._ Pertaining to an embryo; being an embryo; not yet hatched.

ENAM´EL, _n._ The hard white substance covering the teeth.

ENARTHRO´SIS, _n._ Ball-and-socket joint.

ENCEPH´ALON, _n._ Contents of the cranium, especially the brain.

ENDOCAR´DIUM, _n._ Lining membrane of the heart.

ENDOG´ENOUS, _a._ Of internal growth or formation; interstitially deposited. Compare _autogenous_. Opposed to _exogenous_.

ENDOSKEL´ETON, _n._ The skeleton proper, or skeleton as commonly understood; the inner bony framework of the body. (Used in distinction from _exoskeleton_ or _dermoskeleton_, such as some animals possess.)

ENTER´IC, _a._ Belonging or relating to the intestines; intestinal.

ENTO- (_in composition_). Inner.

EPENCEPH´ALON, _n._ Hindmost segment of the brain.

EPI- (_in composition_). On; upon; over. Opposed to _hypo-_.

EPIDER´MIS, _n._ Cuticle or scarf-skin.

EPIDID´YMIS, _n._ An associate organ of the testis, in birds apparently a remnant of the primordial kidney.

EPIGAS´TRIUM, _n._ Pit of stomach; upper belly, next to breast. (A region not well distinguished in birds. The term is scarcely used.) (64.)

EPIGLOT´TIS, _n._ Gristly flap on top of windpipe, rudimentary or wanting in birds.

EPIGNATH´OUS, _a._ Hook-billed.

EPIOT´IC, _a._ for _n._ A certain element of the auditory capsule.

EPIPH´YSIS, _n._ Gristly cap on the end of a bone, afterward becoming bony and united.

EPIPLEU´RA, _n._ An obliquely backward bony process of a vertebral rib.

EPITHE´LIUM, _n._ Superficial layer of mucous membrane. Sometimes also the thick tough membrane lining the gizzard.

EPITHE´MA, _n._ Horny excrescence upon the bill.

EPIZO´ÖN, _n._ An external parasite.

EPIZOÖT´IC, _a._ Parasitic among animals.

EREC´TILE, _a._ Susceptible of being raised, as a crest; or capable of swelling and stiffening, as a penis.

ER´YTHRISM, _n._ A particular state of plumage characterized by excess of red pigment; it is well shown in _Scops asio_ and other owls. (Compare _albinism_ and _melanism_.)

ETH´MOID, _n._ One of the cranial bones, in the nasal region.

ETYP´ICAL, _a._ Of exceptional character. Tending away from a particular type. Opposed to _attypical_.

EUSTA´CHIAN (_tube_), _a._ for _n._ The air-tube from the fauces to the inner ear.

EVEN (_tail_), _a._ Having all the feathers of equal length. Also called _cauda æqualis_ or _integra_.

EX- (_in composition_). Out; out of; away from.

EXCRES´CENCE, _n._ Outgrowth, fleshy or cutaneous.

EXCRE´TA, _n. pl._ Excrement, or other animal refuse.

EX´CRETORY or EX´CRETIVE, _a._ Having power or quality of excreting. _Excreting_ differs from secreting, in that the substance resulting is to be eliminated from the economy, not used; e.g. saliva is _secreted_; urea is _excreted_.

EXOCCIP´ITAL, _a._ or _n._ One of the lateral elements of the occipital bone.

EXOG´ENOUS, _a._ Produced by outgrowth.

EXOSTO´SIS, _n._ Any morbid bony outgrowth or enlargement.

EXTEN´SOR, _n._ Generic name of muscles that extend or straighten a limb or any of its segments.

EXTE´RIOR TOES. (126.)

EXTREM´ITY, _n._ Any limb, member; equal to _membrum_, _artus_.

EY´AS, _n._ An unfledged hawk.

EYE´BROW, _n._ (43.) See SUPERCILIUM.

EY´RY or EY´RIE, _n._ Nest of a bird of prey.

F.

FABEL´LA, _n._ A certain sesamoid bone.

FA´CET, _n._ Smooth, flattened articulating surface.

FA´CIAL, _a._ Pertaining to the face.

FA´CIES, _n._ Face; whole front of head, excepting the bill.

FÆ´CAL, _a._ Pertaining to excrement; excrementitious.

FÆ´CES, _n. pl._ Excrement; dung.

FAL´CATE, FAL´CIFORM, _a._ Sickle-shaped; scythe-shaped.

FAL´CONINE, _a._ Like a hawk; belonging to the _Falconidæ_.

FALSE WING. (79.) See ALULA.

FALX CEREBRI, _n._ A certain fold of the _dura mater_.

FAMILY, _n._ Systematic group of the grade between order and genus, generally distinguished or denoted by the termination _-idæ_, as _Falcon-idæ_.

FAS´CIA, _n._ Broad band of color. Also, equivalent to APONEUROSIS (which see).

FAS´CIATED, _a._ Broadly banded with color.

FAS´CICLE, _n._ Bundle.

FAS´CICLED, FASCIC´ULATE, _a._ Bundled.

FASTIG´IATE, _a._ Bundled together into conical shape, or with enlarged head, like a wheat-sheaf.

FAU´CES, _n._ The jaws, internally; back of the mouth. Compare PHARYNX.

FEATHER, _n._ (1; 143.) See PLUMA, PENNA. Any one of the objects which collectively constitute the peculiar covering of birds.

FEC´ULENT, _a._ Excrementitious.

FECUN´DATED, _a._ Impregnated; made fruitful; said of the germ of an egg which has received the male element.

FECUNDA´TION, _n._ Impregnation; the usual consequence of the completed joint act of the ovarian and spermatic organs.

FECUN´DITY, _n._ Fruitfulness.

FEM´ORAL, _a._ Pertaining to the thigh, or part of leg from hip to knee.

FE´MUR, _n._ Thigh-bone. Also used synonymously with _thigh_. (97.)

FENES´TRATE, _a._ Furnished with openings (from _fenestra_, a window).

FE´RAL, _a._ Wild; not tamed. Opposed to _domestic_. The mallard is the _feral_ stock of the tame duck.

FERRUGIN´EOUS or FERRU´GINOUS, _a._ Rusty-red.

FE´TUS or FŒ´TUS, _n._ Unborn young. (But the unhatched young of birds are oftener called _embryos_.)

FIBRIL´LA, _n._; pl. _fibrillæ_. Little fibre.

FIB´RIN, _a._ Certain animal substance of fibrous composition, found in the blood and elsewhere.

FI´BRO-CAR´TILAGE, _n._ A kind of cartilage of fibrous structure, such as that between vertebræ and many other joints.

FIB´ULA, _n._ Smaller outer leg-bone, lying alongside the tibia.

FIL´AMENT, _n._ Thread or slender fibre.

FILAMENT´OUS, FIL´IFORM, _a._ Threadlike; composed of filaments; oftener, very narrowly linear.

FILOPLUMA´CEOUS, _a._ Having the structure of a filoplume.

FIL´OPLUME, _n._ Thread-like or hair-like feather; one with slender scape, and without web in most or all of its length.

FIM´BRIATED, _a._ Fringed.

FISSIPAL´MATE, _a._ Lobiped and semipalmate, as a grebe’s foot is.

FIS´SIPED, _a._ Having cleft toes. Opposed to _palmiped_.

FISSIROS´TRAL, _a._ Having the bill cleft far beyond the base of its horny part.

FISSIROS´TRES, _n._ An obsolete order of cleft-billed birds.

FLAM´MULATED, _a._ Pervaded with reddish color.

FLANK, _n._ Hinder part of side of trunk. (67.)

FLAP, _n._ See LOMA.

FLEX´ION, _n._ Bending (of a limb). Opposed to _extension_.

FLEX´OR, _n._ Generic name of a muscle that bends a limb or any of its segments.

FLEXU´RA (_alæ_), _n._ Bend of the wing; carpal angle; salient angle or prominence formed at the wrist when the wing is folded. (77.)

FLEX´URE, _n._ See FLEXURA.

FLOC´CULENT, _a._ Pertaining to the peculiar down of newly hatched or unfledged young birds. (Not used in ornithology in its common sense of _flaky_.)

FLOC´CUS, _n._ A peculiar kind of plumage of simple structure (generally downy), found in unfledged birds, at first growing directly from the skin, afterwards for the most part affixed to the tip of the true feather, of which it is the precursor, or rather the first-formed part; and finally falling off. In psilopædic birds the floccus is only associated with the true plumage, sprouting from the future pterylæ alone; in ptilopædic birds it also sprouts from the apteria, and in so far is unconnected with future plumage; the whole body is in such cases densely clothed. (_Sundevall._)

FΫTUS, _n._ Same as FETUS (which see).

FOL´LICLE, _n._ Minute secretory sac.

FOLLIC´ULAR, FOLLIC´ULATE, _a._ Having follicles; composed of follicles.

FOOT, _n._ (112.) See PES.

FOOT-JOINT, _n._ Junction of toes collectively with the metatarsus. (100.) See PODARTHRUM.

FORA´MEN, _n._; pl. _foram´ina_. Hole; opening; perforation. _Foramen magnum_, the large hole in the occipital bone transmitting the neural axis. _Foramen lacerum_, irregular vacuity between certain bones at base of skull. The _foramen rotundum_ transmits the optic nerve; _foramen ovale_, the trigeminal nerve; the latter is also a name of the opening between right and left sides of the heart.

FORE´HEAD, _n._ Front of head from bill to crown. (34.) See FRONS.

FORE-NECK, _a._ Whole front of collum, from chin to breast; whole throat. (51.) See GUTTUR.

FOR´FICATE, _a._ Deeply forked.

FORKED (_tail_), _a._ Having the outer feathers longest, the rest gradually successively shortened to the middle pair; when these are again lengthened somewhat, the tail is said to be _doubly forked_.

FOS´SA, _n._; pl. _fossæ_. Ditch; excavated place. Used chiefly in the plural to denote the pits or grooves in which most birds’ nostrils open.

FOS´SIL, _a._ or _n._ Dug out of the ground. Particularly, any organized body, or remains, trace, or mould of such body, naturally buried in past time by geologic agencies. The _Archæopteryx macrurus_, of the Jurassic formation of Solenhofen, a mesozoic bird, is the oldest known ornithic _fossil_.

FOSSO´RIAL, _a._ Digging into the earth for a habitation.

FOS´TER. This word and its various compounds are used in their common senses in treating of the relations of young cowbirds and young cuckoos with the birds upon which they are parasitic.

FO´VEA, _n._ A slight depression.

FREE, _a._ Said of the leg when not enclosed to the knee in the common integument of the body.

FRE´NUM, _a._ Bridle; hence, any cheek-stripe.

FRINGE, _n._ Marginal membrane; also, marginal row of feathers. (135.) See LOMA.

FRINGED TOE. (134.)

FRONS, _n._ Forehead. (34.)

FRON´TAL, _a._ Pertaining to the forehead.

FRON´TAL BONE, _n._ Principal bone of the forehead.

FRON´TAL POINTS. See ANTIÆ. (36.)

FRONT OF TARSUS. Instep. (104.)

FRUGIV´OROUS, _a._ Fruit-eating.

FULIG´INOUS, _a._ Sooty-brown; dark smoky brown.

FUL´VOUS, _a._ Of a brownish-yellow color.

FUR´CATE, _a._ Forked; forficate.

FUR´CULA or FUR´CULUM, _n._ The merry-thought or wish-bone; the two clavicles or collar-bones taken together. Also called _os furcatum_.

FUS´COUS, _a._ Of a dark-brown color.

FU´SIFORM, _a._ Spindle-shaped; tapering at each end.

G.

GAL´EATE, _a._ Covered as with a helmet; said of certain gallinules, coots, etc.

GALL, _n._ Bile; the secretion of the liver.

GALL-BLAD´DER, _n._ Membranous sac attached to liver for holding bile.

GALL-DUCT, _n._ Tube for conveyance of bile into the intestine; the _ductus choledochus_.

GALLINA´CEOUS, _a._ Belonging to the _Gallinæ_; having the nature of the domestic fowl.

GANG´LION, _n._; pl. _ganglia_. Natural knot-like enlargement of a nerve.

GAPE, _n._ Opening of the mouth; area of the opened mouth. (28.) Compare RICTUS and COMMISSURE.

GASTRÆ´UM, _n._ The whole under part of a bird. (16.)

GAS´TRIC, _a._ Pertaining to the stomach or belly. The _gastric_ juice of birds is the secretion of the _proventriculus_, or follicular stomach, not of the gizzard or grinding muscular stomach.

GASTROCNE´MIUS, _n._ A muscle of the back of the leg.

GEMEL´LI, _n. pl._ The twins; certain muscles of the pelvis.

GE´NA, _n._ Cheek; feathered side of under mandible. (43.) See MALAR REGION.

GEN´ERATIVE OR´GANS, _n._ Organs of reproduction in either sex.

GENER´IC, _n._ Pertaining to a genus; as, _generic_ character, _generic_ description.

GEN´ESIS, _n._ Act, mode, or conditions of reproduction. In science, _genesis_ notes rather the laws and results of origination of individuals or species. The “genesis of species” is a term equivalent to the evolution of species from antecedent forms, with some; with others, their origination by creative fiat.

GENET´IC, _a._ Pertaining to genesis. _Genetic_ descent, or _genetic_ succession in species, is maintained by those who hold the theory of evolution.

GE´NU, _n._ Knee; joint of femur with tibia.

GE´NUS, _n._; pl. _gen´era_. An assemblage of species, or a single species, constituting a taxonomic group of value next below that of the family.

GEN´YS, _n._ See GONYS.

GER´MINAL VES´ICLE, _n._ Cell in the vitellus having a dark spot.

GIBBOSE´, GIB´BOUS, _a._ Swollen; protuberant; humped; hunched.

GIBBOS´ITY, _n._ A swelling or protuberance.

GIGE´RIUM, _n._ Gizzard.

GIN´GLYMUS, _n._ Hinge-joint. The knee and elbow are _ginglymoid_, or hinged joints.

GLAB´ROUS, _a._ Smooth.

GLAND, _n._ A soft fleshy organ, in which fluids of the body are modified to form new products, to be used in, or eliminated from, the economy. But some organs without ducts, and the function of which is unknown, are called _glands_, as the thymus, thyroid, and pineal. The liver is the largest _gland_ of the body. The proventriculus is a _glandular_ organ.

GLAN´DULAR, _a._ Pertaining to glands; having glands; consisting of glands.

GLANS, _n._ Head of the penis.

GLOS´SA or GLOT´TA, _n._ Tongue.

GLOS´SO-HY´AL, _n._ Principal bone of the tongue.

GLOS´SO-PHARYN´GEAL, _a._ Pertaining to the tongue and jaws. A certain nerve is so called.

GLU´TÆAL, _a._ Pertaining to the buttocks; certain muscles are so called.

GLU´TÆUS, _n._ A muscle of the side of the rump.

GNATHID´IUM, _n._; pl. _gnathidia_. Branch of the lower jaw as far as it is naked. (Oftener used in the plural.) (24.)

GNATHOTHE´CA, _n._ Covering of the lower mandible. (14.)

GONYDE´AL, _a._ Pertaining to the mandibular symphysis.

GO´NYS, _n._ Keel or lower outline of the bill as far as the mandibular rami are united. (The word is commonly but erroneously so written, as if from the Greek _gonu_, knee, or protuberance of the bill; it is rather from the Greek _genus_ (_genys_), signifying chin.—_Sundevall._)

GOR´GET, _n._ Throat-patch, distinguished by color or texture of the feathers.

GRA´DIENT, _a._ Walking or running by steps. Opposed to _saltatory_, or leaping.

GRAD´UATED, _a._ Changing length at regular intervals, in regular succession; said chiefly of the tail when its feathers regularly shorten successively by more and more from the middle to the outer.

GRAMINIV´OROUS, _a._ Grass-eating.

GRANIV´OROUS, _a._ Seed-eating.

GRAN´ULATE, _a._ Roughened with numerous small elevations, like shagreen. (Said chiefly of the tarsus.)

GREATER WING-COV´ERTS, _n._ The single, longest, most posterior series of the secondary set. (92.)

GROUND-COL´OR (_in oölogy_), _n._ The color of the general surface of the egg-shell, as distinguished from its markings.

GRYPAN´IUM, _a._ Noting a particular form of bill, in which the culmen is nearly straight, but bent down at the tip.

GU´LA, _n._ Upper foreneck, adjoining chin; upper throat. (52.)

GU´LAR, _a._ Pertaining to the upper foreneck.

GUT´TATE, _n._ Having drop-shaped spots.

GUT´TIFORM, _a._ Drop-shaped.

GUT´TUR, _n._ The whole foreneck. (51.) (But _guttural_ is rarely used in this connection.)

GYMNOPÆ´DIC, _n._ Synonymous with _psilopædic_.

GYMNORHI´NAL, _a._ Having unfeathered nostrils.

H.

HAB´ITAT, _n._ Locality or region frequented by a species; its geographical distribution.

HAB´ITUS, _n._ Habitude; mode of life.

HACK´LE, _n._ Long cervical feather of the domestic cock.

HÆ´MAL ARCH, _n._ The lower ring of a (ideally or actually) complete vertebra, enclosing a section of the principal vascular and visceral systems, as the neural arch does a section of the principal nervous system. In birds the hæmal arch is complete only in the thoracic region.

HÆ´MAL SPINE, _n._ An ideal transverse section of the sternum corresponding to any one pair of ribs, completing the hæmal arch inferiorly.

HÆMAPOPH´YSIS, _n._ Segment, actual or potential, of the hæmal arch between the pleurapophysis and hæmal spine. In birds it actually exists in the thoracic region, as the _sternal rib_, movably articulated with the sternum and the vertebral rib, which latter is the pleurapophysis.

HÆMATIT´IC, _a._ Of a bloody-red color.

HÆMATOTHER´MA, _n._ Warm-blooded animals collectively; the antithesis is _hæmatocrya_.

HAL´LUCAL, _a._ Pertaining to the hallux.

HAL´LUX, _n._ The hind toe. The name is retained, even when the hind toe is brought round to the front. When the toes are in pairs, it is the inner of the two hind ones, excepting in _Trogonidæ_. In the genus _Picoides_ the actual single hind toe is not the hallux, but the fourth toe reversed, there being no hallux. This toe may always be recognized by presence of not more than two joints. It is the one usually wanting in three-toed birds, and is frequently rudimentary or functionless, even when present. Its large size, with largest claw, and specialization of its flexor muscle, marks the passerine or highest group of birds. (129.) (Sometimes written _hallex_ or _allex_.)

HALO´NES, _n. pl._ Certain appearances of the yolk, probably due to the margins of its successive layers.

HAM´ULATE, _a._ Hooked.

HAM´ULUS, _n._; pl. _hamuli_. Hooked fringe of a barbule; hooked barbicel.

HAND-QUILLS, _n._ Primary remiges. (75.)

HAS´TATE, _a._ Spear-head shaped.

HEAD, _n._ (9, 29.)

HEEL, _n._ (107.) See CALCANEUS and TALUS. Upper back part of tarso-metatarsus (tarsus or shank), rarely resting on the ground in birds when standing erect. (Commonly, but most improperly, called _knee_.)

HEEL-JOINT, _n._ (103.) See SUFFRAGO. The tibio-tarsal articulation, as it is called; that between the leg (crus), and the tarso-metatarsus (shank). With few exceptions among certain _Raptores_, it always bends backward; the _knee_ always has its convexity forward.

HEEL-PAD, _n._ (115.) Pterna; tuber (which see). The posterior portion of _pelma_, immediately under the foot-joint, and frequently prominent. (But _heel-pad_ should not be used in this connection, since the _heel_ (_calcaneus_) is at the top of the tarsus, and not at the bottom where the _heel-pad_ lies.) (115.)

HEMI- (_in composition_). Semi-; demi-; half.

HEPAT´IC, _a._ Pertaining to the liver; as, _hepatic_ artery, _hepatic_ secretion.

HETEROGE´NEOUS, _a._ Of different or dissimilar nature; of mixed or miscellaneous character.

HEX´AGON, _n._ Figure of six sides and six edges.

HEXAG´ONAL, _a._ Having six sides and edges.

HIBER´NAL, _a._ Pertaining to the winter time. (Neither this nor _æstival_ are much used, although _vernal_ and _autumnal_ are continually employed.)

HIND-NECK, _n._ (48.) See CERVIX.

HIND-TOE, _n._ (129.) See HALLUX.

HINDER PARTS. (8.) See URÆUM.

HIP, _n._ Joint of femur with pelvis; projection formed by femoral trochanter over the joint.

HIRSUTE´, _a._ Hairy; rather shaggy, as the feet of a grouse.

HISTOG´ENY, _n._ Formation of tissue.

HISTOL´OGY, _n._ Minute anatomy; history of tissue.

HISTON´OMY, _n._ Laws of formation of tissue.

HOAR´Y, _a._ Of a pale silvery-gray.

HOLORHI´NAL, _a._ Having the nasal bones contiguous.

HOMOGENE´ITY, _n._ Sameness; structural similarity.

HOMOGE´NEOUS, _a._ Of the same kind or nature. Opposed to _heterogeneous_. A _homogeneous_ group contains only structurally related forms.

HOMOLOG´ICAL, HOMOL´OGOUS, _a._ Structurally related; having structural affinity. Opposed to _analogous_, which implies similarity of appearance, purpose, or use without corresponding affinity.

HOMOL´OGY, _n._ Structural affinity, generally implying genetic relationship. Opposed to _analogy_, or mere resemblance.

HOMOTYP´ICAL, _a._ Of the same type of structure.

HOMOT´YPY, _n._ A particular kind of homology.

HOR´NOTINE, _a._ or _n._ Yearling; a bird of the year.

HU´MERAL, _a._ Pertaining to the humerus, or, more generally, to the upper arm.

HU´MERUS, _n._ The upper arm bone; sometimes the whole upper-arm, from shoulder to elbow.

HY´ALINE, HY´ALOID, _a._ Transparent, like glass; said chiefly of the vitreous humor of the eye, and of certain appurtenances of the back chamber of the eye.

HY´BRID, _a._ or _n._ Cross-born between two species; mongrel.

HYBRIDIZA´TION, _n._ Cross-fertilization. Production of hybrids.

HY´BRIDIZE. To cross and bear mongrel offspring.

HY´OID, HYOID´EAN, _a._ Pertaining to the _os hyoides_ or tongue-bone, or, more generally, to the tongue itself.

HYPAPOPH´YSIS, _n._ Bony process from the under side of a vertebra, sometimes very large, as in the loon.

HYPER- (_in composition_). Same as _super-_ (which see).

HYPERBO´REAN, _a._ Northern; boreal.

HYPERCHROM´ATISM, _n._ State of unusually increased or intensified coloration.

HYPER´TROPHY, _n._ Inordinate enlargement of a part or organ, due to excessive nutrition. The opposite of _atrophy_, or the wasting away of an organ through deficient nutrition.

HYPO- (_in composition_). Same as _sub-_ (which see).

HYPOCHON´DRIUM, _n._ The flank. (Oftener used in the plural, _hypochondria_, flanks.) (67.)

HYPODAC´TYLUM, _n._ Soles of the toes. (118.)

HYPOGAS´TRIC, _a._ Under or behind the belly. (Little used).

HYPOGNATH´OUS, _a._ Having the under mandible longer than the upper, as the black skimmer.

HYPOPTI´LUM, _n._ Supplementary plume, or accessory plume, springing from the same barrel of the main feather. Generally found, but wanting in many families, and always on the quills of the wings and tail. Synonymous with _hyporrhachis_ as generally used.

HYPORA´DII, _n. pl._ Barbs of the hypoptilum.

HYPORRHA´CHIS, _n._ Aftershaft; stem or scape of the supplementary plume. Generally used for the whole of such accessory feather, but best thus restricted.

HYPOTH´ESIS, _n._ A reasonable presumption or supposition taken as premise of an argument, or as probably true, to account for what is not understood. As it does not necessarily rest upon fact, it has not the weight or dignity of _theory_.

HYPOTHET´ICAL, _a._ Reasonably presumptive: logically supposititious; conditional; assumed without proof but with fair probability.

I.

IDENTIFICA´TION, _n._ Act or process of determining to what species a specimen or a name belongs; the determination so made.

IDEN´TIFY. To determine the name of a specimen or of a species; to ascertain the identity of a certain specimen with a name, or name with a certain species.

IGNO´BLE, _a._ Said of hawks lacking the special qualities of those used in falconry.

IL´EUM, _n._ Lower portion of small intestine.

IL´IAC, _a._ Relating to the ilium, or haunch-bone; also, to the ileum.