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Webster 1913 Edition
Spiracle
1.
(Anat.)
The nostril, or one of the nostrils, of whales, porpoises, and allied animals.
2.
(Zool.)
(a)
One of the external openings communicating with the air tubes or tracheae of insects, myriapods, and arachnids. They are variable in number, and are usually situated on the sides of the thorax and abdomen, a pair to a segment. These openings are usually elliptical, and capable of being closed. See Illust. under
Coleoptera
. (a)
A tubular orifice communicating with the gill cavity of certain ganoid and all elasmobranch fishes. It is the modified first gill cleft.
3.
Any small aperture or vent for air or other fluid.
Webster 1828 Edition
Spiracle
SPIR'ACLE
,Noun.
1.
A small aperture in animal and vegetable bodies, by which air or other fluid is exhaled or inhaled; a small hole, orifice or vent; a pore; a minute passage; as the spiracles of the human skin.2.
Any small aperture, hole or vent.