tetrapneumona
Tet`ra*pneu"mo*na, n. pl. Etym: [NL. See Tetra-, and Pneumo-.] (Zoöl.) Defn: A division of Arachnida including those spiders which have four lungs, or pulmonary sacs. It includes the bird spiders (Mygale) and the trapdoor spiders. See Mygale.