112 



FIRST LESSOm IN ZOOLOGY. 



(mesothorax). The latter forms the greater part of the tho- 

 rax. It consists of three large upper pieces, the prcescuium, 

 scutum, and the triangular or shield-shaped seutellum (Fig. 



Fig. 132.— Nerves of the tongue. Ig, labellar glands; th, taoffle hairs; gb, gland- 

 bristles; n, nerve — Figs. 119-182 after Kraepelin. 



123, set'). To the side of this segment are attached the 

 two wings. The third ring (metathorax) is but partly 



Fio. 123.— Thorar of the house-fly. pi-m, pronotum; pj-.sc, praesoutum; sc', 

 mesoscutura : sti', mesoscutellum; psrt', postscutelluni; a/, Insertion of 

 alula, extending to the insertion of the wing?, which have been removed ; 

 msphr, mesophragma; h, balancer (halter; /it, patagia; nitn, metano- 

 tum; epis. epis'. epis'. epistemum of pro-, meso- and meta-thorax; <-pm'. epm', 

 meso- and meta-epimerum: .9^. s/". meso- and meta-sternum; ca;', ca;', ca;'", 

 coxae; fr'. tr'. tr'". trochanters of the three pairs of legs; sp'. sp'. sp"\ sp"", 

 up'"", first to fifth spiracles; tg', ty\ tergites of first and second abdominal seg- 

 ments; u\ tt", urites. 



formed, and cannot be seen from aboye. It supports the 

 balancers (Fig. 123, h), which are in reality the- hind wings. 



