2. (Zoöl.) (a) One of the external openings communicating with the air tubes or tracheæ 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.
Spiracular
(Spi*rac"u*lar) a. Of or pertaining to a spiracle.
Spiræa
(Spi*ræ"a) n. [L., fr. Gr. fr. a coil.] (Bot.) A genus of shrubs or perennial herbs including the meadowsweet
and the hardhack.
Spiræic
(Spi*ræ"ic) a. (Chem.) Of, pertaining to, or derived from, the meadowsweet (Spiræa); formerly, designating
an acid which is now called salicylic acid.