258 



W. WESCHE. 



TABLE VI. 



STRUCTURE OF THE EYES IN BRACHYCERA AND CYCLORRHAPHA. 



1 In Leptogaster cylindrica Deg. (exceptional) 9 



2 Often squares. 



3 The three stages have been found in the eyes of H. pluvialis in cf. 



4 Opetia exceptional. 



With regard to the phylogeny of the Cyclorrhapha I have 

 endeavored to show by a comparison of the mouthparts and 

 venation, to which I may add the eye structure and general 

 morphology, that the Tabanidae stand close to the ancestral 

 forms of the Cyclorrhapha, though the Syrphidae and Conopidae 

 branched off when the insects had complete mouthparts and 

 ocelli, long before the Muscidae became the specialized and 

 dominant group that it now is. 



Williston says (page 332) that "every family save the Tipulidae 

 is, I believe, absolutely excluded from immediate genetic relations 

 with the Brachycera, because of the venation and antennae." 

 I do not know of any anatomical structure that militates against 



