The Collaborative International Dictionary of English v.0.48:

Mygale \Myg"a*le\, prop. n. [L., a field mouse, Gr. ?.] (Zool.)
   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).
   [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Tarantula \Ta*ran"tu*la\, n.; pl. E. Tarantulas, L.
   Tarantulae. [NL., fr. It. tarantola, fr. L. Tarentum, now
   Taranto, in the south of Italy.] (Zool.)
   Any one of several species of large spiders, popularly
   supposed to be very venomous, especially the European species
   (Tarantula apuliae). The tarantulas of Texas and adjacent
   countries are large species of Mygale. [Written also
   tarentula.]
   [1913 Webster]

   Tarantula killer, a very large wasp (Pompilus formosus),
      which captures the Texan tarantula (Mygale Hentzii) and
      places it in its nest as food for its young, after
      paralyzing it by a sting.
      [1913 Webster]