- The ear drum, or middle ear. Sometimes applied
incorrectly to the tympanic membrane. See Ear. - A chamber in the anterior part of the syrinx of birds. - One of the naked, inflatable air sacs on the neck of the
prairie chicken and other species of grouse. - The recessed face of a pediment within the frame made by
the upper and lower cornices, being usually a triangular space or
table. - The space within an arch, and above a lintel or a
subordinate arch, spanning the opening below the arch. - A drum-shaped wheel with spirally curved partitions by
which water is raised to the axis when the wheel revolves with the
lower part of the circumference submerged, -- used for raising water,
as for irrigation.
- The outermost of the three small auditory bones, ossicles;
the hammer. It is attached to the tympanic membrane by a long process,
the handle or manubrium. See Illust. of Far. - One of the hard lateral pieces of the mastax of Rotifera.
See Mastax. - A genus of bivalve shells; the hammer shell.
- The boss of a shield, at or near the middle, and usually
projecting, sometimes in a sharp spike. - A boss, or rounded elevation, or a corresponding depression,
in a palate, disk, or membrane; as, the umbo in the integument of the
larvae of echinoderms or in the tympanic membrane of the ear. - One of the lateral prominence just above the hinge of a
bivalve shell.
- An axis to which a carpel of a compound pistil may be
attached, as in the case of the geranium; or which is left when a pod
opens. - A columnlike axis in the capsules of mosses. - A term applied to various columnlike parts; as, the
columella, or epipterygoid bone, in the skull of many lizards; the
columella of the ear, the bony or cartilaginous rod connecting the
tympanic membrane with the internal ear. - The upright pillar in the axis of most univalve shells. - The central pillar or axis of the calicles of certain
corals.