• Webster's Revised Unabridged Dictionary
    • n. pl Tetrapneumona (Zoöl) 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.
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Century Dictionary and Cyclopedia
    • tetrapneumona A division of Araneina, or true spiders, having four lungs, four spinnerets, and eight approximated ocelli: distinguished from Dipneumones. It consists of the mygalids or theraphoses, the bird-spiders of South America, the tarantulas of North America, and the trap-door spiders. Also Tetrapneumones.
    • tetrapneumona A group of holothurians, represented by the genus Rhopalodina, having four water-lungs (whence the name). Schmarda. Also called Decacrenidia, Diplostomidea, and Rhopalodinæ.
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Webster's Revised Unabridged Dictionary
NL. See Tetra-, and Pneumo-