EXTERNAL STRUCTURE. 



The Thorax. 



The thorax is divided into four segments, the prothorax, meso- 

 thorax, metathorax, and epinotum. The epinotum (which is the 

 metanotum of some earlier writers and the propodeum of others) 

 was the first abdominal segment of the larva, which has been 

 fused to the thorax during pupation. 



In the primitive form, all the component parts of the thorax of 

 the male ant are distinctly separated by sutures. 



The prothorax is small and is divided into the pronotum and 

 prosternum ; the former comprises both dorsally and laterally the 

 greater part of the prothorax, while the latter is small and narrow, 

 and to it the coxa of the fore leg is articulated. 



Scutum of Fore Prae- 



Tegula mesonotum wing scutellum 



Hind wing 



Scutellum 



Metanotum 



Epimeron of 

 metathorax 



Epinotum 



Episternite of 

 mesothorax 



Sternite of Episternite of 

 mesothorax metathorax 



Fig. 6. Thorax of Streblognathus aethiopicus <. (Emery.) 

 1, 2, 3, and 4 stigmata of meso- and metathorax, epinotum, and petiole. 



The mesothorax is large and bears the fore-wings ; its anterior 

 dorsal portion, the scutum of the mesonotum, often spoken of as 

 the mesonotum, bears in many male ants a Y-shaped furrow, called 

 the Mayrian furrow, and on either side is a longitudinal suture, 

 the parapsidal furrow, which separates off the area known as the 

 parapsis. The prae- scutellum ( =paraptera of Emery) of the meso- 

 thorax, is situated at the posterior end of the scutum behind the 

 articulation of the fore -wings. Covering the insertion of the fore- 

 wing a chitinous scale, the tegula, occurs. The scutellum, a large 

 semi-circular plate, is situated between the prae-scutellum and the 

 metanotum. The coxa of the intermediate leg is articulated to the 

 mesosternum ; between this and the pronotum is the episternite of the 

 mesothorax, and above the latter is the epimeron of the mesothorax. 

 The metanotum, the dorsal part of the metathorax, consists of a 

 narrow band between the scutellum and the epinotum, and on either 



