A UDITOR Y AND SO UND-PROD UCING MECHA NISMS. 603 



11. THE HALTERES OF THE BLOW-FLY. 



a. General Structure and Morphology (Plates XLII. and XLIII.). 



The halteres, which are commonly known in the Diptera 

 as ' balancers,' are rarely absent in the order. Weismann [2] 

 showed that they are developed from the upper metathoracic 

 imaginal discs, and they are now generally admitted to be 

 homologous with the posterior wings of other insects. 



When it is said, however, that they are rudimentary wings, 



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Muthmassungen iiber den Flug und das Gesumme einiger Zweifliigler 

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289. AUDOUIN, V., Art. ' Balancier.' Dictionnaire classique d'Hist. Nat., 



torn. vi. et viii., 1820-1822, Paris. 



290. ROBINEAU-DESVOIDY, ' Einiges u. die Thatigkeit der Schvvinger.' 



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