mesosoma

from The Century Dictionary.

• noun In lamellibranchiate mollusks, a middle region of the body, which gives rise to the foot and is situated between the prosoma and the metasoma.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun zoology The middle part of the body, or tagma, of arthropods whose body is composed of three parts (the other two being the prosoma and the metasoma), bearing the legs and (in winged insects) the wings.