Webster's Revised Unabridged Dictionary · 1913

(Zoology) A genus of very large hairy spiders of the family Ctenizidae, having four lungs and only four spinnerets. They do not spin webs, but usually construct tubes in the earth, which are often furnished with a trapdoor. The South American bird spider (Mygale avicularia), and the crab spider, or matoutou (Mygale cancerides) are among the largest species. They are also called trapdoor spiders. Some of the species are erroneously called tarantulas, as the Texas tarantula (Mygale Hentzii).