Definition of "mesothorax" [mes•o•tho•rax]

• The middle of the three divisions of the thorax of an insect, bearing the middle pair of legs and the first pair of wings. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Vertebrates, the skeleton of the prothorax to the bones of the cerebellum, of the palate, and the pieces of the larynx, the skeleton of the mesothorax to the parietals, interparietals, and opercular bones, and that of the metathorax to the skeleton of the thorax of Vertebrates."
• "Many of the names which he proposed are still in use; it was he who introduced the terms prothorax, mesothorax, and metathorax, for the three segments of the insect's thorax."
• "He used Geoffroy's _Loi de balancement_ to explain cases of correlative development, such as the relation between the size of the front wings and the development of the mesothorax."