ANTS. 



nun. which, of course, is serially homologous with the mesonotum, is 

 very narrow antero-posteriorly and separated from the mesonotum by 

 a large, unpaired, semi-circular element, the scutellum. Between the 

 scute-Hum and metanotum, a small piece, the metaparapteron, or post- 

 scutellum, is intercalated on each side. The hind-wing is inserted 



between this metaparapteron and the 

 metepimeron. The epinotum. which, as 

 we have seen, is morphologically the 

 first abdominal segment, is large and 

 convex and in many ants furnished with 

 a pair of stout spines or teeth. It is 

 closely applied to the metathorax from 

 the posterior edge of the mesonotum 

 above to the ventral edge of the meta- 

 thorax below. 



The thorax has on each side three 

 openings, or stigmata, to the respiratory 

 tubes, or tracheae. The first, belonging 

 morphologically to the mesothorax. lies 

 FIG. 7. Dorsal aspect of beneath a small flap-like expansion of 



thorax of male Ponerine ant, . , 



Paraponcra clavata. (Emery.) the pronotlim where it abuts oil the 



a' and a", Anterior and posterior mesepimeron. The second or meta- 



wings ; pn, pronotum ; sc, scutum , . 1-1 ^ ^ 



of mesonotum; sM, Mayrian thoracic stigmata lies beneath the mser- 

 furrow ; fss, parapsidal furrow ; tion of the hind-wing and near the pos- 



pps, parapsis ; teg, tegula ; ppt . . , . ,. 



and ppt', paraptera of meso- and tenor end f the mesepimeron. The 



metathorax ; set, scutellum ; nitii. third stigma, belonging to the first ab- 



metanotum ; cf>n, epinotum; pet, . , .... 



petiole. dominal segment, is distinctly seen on 



the side of the epinotum. 



In the female ant ( Fig. 8, A ) the thorax is constructed on the same 

 plan as that of the male, but is more robust and lacks the Mayrian 

 furrow, which is also absent in the males of many genera. The males 

 and females of most species, however, exhibit a greater simplification 

 of the pleural region of the thorax, owing to the fusion of the epimera 

 and episterna with each other and often also with the sterna in the 

 meso- and metathorax, and a very intimate fusion of the epinotum with 

 the latter segment. 



Turning to the workers, which are wingless, there is noticeable a 

 great reduction in the size of the meso- and metathorax [>lns the epi- 

 notum, so that the three divisions of the thorax are more nearly of 

 uniform size (Fig. 8, C, Fig. 9, a). In certain species, and especially 

 in the ergatoid females ( Fig. 8, B) and soldiers of a few genera, the 

 various dorsal elements, such as the paraptera, scutellum and meta- 



