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ARKIV FÖR ZOOLOGI. BAND 4. N:0 10. 



SiLVESTRis' view as to its morphological value seems to 

 me to be quite untenable, firstly because it involves the 

 hypopharynx being situated in the roof instead of in the 

 floor of the mouth cavity, secondly because the labium exhi- 

 bits a structure which is homologous to the hypopharynx 

 and thirdly because in the Diptera Cyclorihapha the maxillse^ 

 when present at all, are always very inconspicuous and 

 stiletto-shaped. 



Textfig. 7. 



Textfig. 7. Thaumatoxena Wasmanni Breddin & Börnek. Dorsal 

 view. X 43- 



The labrum is embraced nearly entirely by a cuticular 

 fold which cowers its proximal half. From its position be- 

 tween the labrum and the headcapsule it is probable that it 

 is homologous with the clypeus. 



* It is notieeable in this respect that there exists great diversity 

 of opinion about these organs. Thus Lowne (The Blowfly. Vol. I. p. 130) 

 says : » ... it is plain that the terminal portion of the proboscis of the 

 imago is developed from the first, and not from the second pair of maxillse. 



