112 



FIRST LESSONS IN ZOOLOGY. 



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

 rax. It consists of three large upper pieces, fheprtBfcutum, 

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



FIG. 122. Nerves of the tongue. Ig, labellar glands; Hi, tactile hairs; yb, gland- 

 bristles; 11, nerve Figs. 119-122 after Kraepelin. 



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

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



pset' 



tc' 



tr" 



FIG. 123. Thorax of the house-fly, prn, pronotum; prsc, proescutum; sc', 

 mesoscutum: art', mesoscutellum ; part', postscutelluni ; nlf insertion of 

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

 nmpltr, mesophragma; //. balancer (halter i; pt, patagia; mtn, metano- 

 tum; epix. epis'. r/tix" . episternum of pro-, meso- andrneta-thorax: epm', epm", 

 meso- and meta-epimerum: */'. */". meso- and meta-sternuin ; CJL-', ex", ex'", 

 coxfe; tr', tr' . tr'". trochanters of the three pairs of legs; xp'. xp", xp'". ftp"", 

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

 ments; ', w", urites. 



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

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



