GLOSSARY OF TECHNICAL TERMS. 85 
Hypopti'lum (L.), n. An accessory plume, attached to the barrel or 
stem of ordinary feathers, excepting always the remiges and rectrices. 
(Essentially the same as after-shaft.) 
Hypora'dii (L. ; pi.), Barbs of the hypotilum, or after-shaft. 
Hyporrha'chis (L.), n. The after-shaft, or stem of the accessory plume, 
or hypoptilum. 
Hypothesis, n. A reasonable presumption to account for what is not 
understood, and hence to be distinguished from theory, based upon 
known facts. 
Hypothetical, a. Reasonably presumptive, or probable, though assumed 
without proof. 
I. 
Identification, n. The determination of the species to which a given 
specimen belongs. 
Identify, v. To determine the systematic name of a specimen. 
Igno'ble (L. igno'bilis), a. Said of certain Hawks used in falconry. Tech- 
nically, applied to the short- winged Hawks (that is, the Goshawk and 
Sparrowhawk), to distinguish them from the noble Ealcons (that is, 
true Falcons). 
iriac (L. ili'acus), a. Pertaining to the flanks. 
Im'bricate, ) (L. imbrica'tus), a. Overlapped, like shingles upon a 
Im'bricated, ) roof. 
Immac'ulate (L. immacula'tus), a. Entirely free from spots or other 
markings. 
Immature', a. Not adult. 
Imperforate (L. imperfora'tus) , a. Not pierced through. 
Incised' (L. inci'sus), a. Cut out; cut away. 
Incubation, n. The act of sitting on eggs in order to hatch them. 
Incum'bent (L. incum'bens), a. Laid at full length. (Said of the hallux, 
or hind toe, when inserted on a level with the anterior toes.) 
Indent'ed (L. indentaftus), a. Notched along the margin with a different 
color. 
In'dian Pur'ple, n. A very dull purple color, like the pigment of the 
same name. (Madder-carmine -f intense blue -f- black.) (Plate VIII. 
% 6.) 
In'dian Red, n. A fine rufous-red color, of a slightly more purplish tint 
than the pigments called Light Red and Venetian Red. Same as 
brick red. (See plate IV. fig. 11.) 
In'dian Yel'low, n. A very intense, rich yellow color, much deeper than 
gamboge, but less pure than cadmium. (Plate VII. fig. 5.) 
Indig'enous, a. Native of a country. 
In'digo Blue (L. indigo'ticus), n. A dark dull blue color, like the indigo 
of commerce. (Plate IX. fig. 1.) 
