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.