THE MEDIAN SEGMENT 



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Pro. 94. T, 8. thorax of Tipula giffantea; 9, of Leptis ; 10, thorax of Tabanus bromius after 

 the removal of the abdomen, in order to bring into view the inner rnesophragma (./), and to show 

 the extension of the metathorax g and g' ; tr, trochanter ; 11, hind end of the mesothorax, the entire 

 metathorax, and the 1st and 2d abdominal segments of Volucella sonaria, seen from the side. The 

 internal mesophragma (./), and the position of the muscle inserted in it, are indicated by the two 

 lines M. p, Callus postalaris ; pr (pz in 8), callus prsealaris Osten Sacken (= " patagium " of some 

 authors); g, metanotum ; g', metepimerum, " segment mediaire " of Latreille (wrongly considered 

 by him to be the 1st abdominal segment) ; 4, metasternum (hypopleura of Osten Sacken) ; 5 (? " epi- 

 sternum of metathorax" (Brauer) = metapleura of Osten Sacken); 6, and also ff, halter; at 1 , 

 mesothoracic stigma ; < 2 , metathoracic stigma ; st 3 , first abdominal stigma ; y, dorsopleural ; 

 5, sternopleural ; e, mesopleural sutures; A, 1st, i, 2d, abdominal segment; al, wing; alul, alula. 

 12, the head and the three thoracic rings, and the 1st abdominal segment of Jfphemera vulgata, 

 the connecting membranes are in white : a, prothorax ; b, priescutum ; c, scutum ; d, scutellum ; 

 e, postscutellum ; ps, postscutellum of mesothorax. After Brauer. 



