Vol. 1.] 



Woor] worth. — M^ing Veins of Insects 



133 



FIG. 79. Wing of a liouse tly. 



fusion of the tips of certain veins and the shifting of the 

 united tips forward. These tendencies are responsible for 

 whatever difficulty there may be in the interpretation of the 

 venations. The figure of Midas (Fig. 78), which is an extreme 

 case, shows the effect of such modification on the general 

 appearance of the venation. 



The Cyclorapha are the most uniform of all the groups in 

 the matter of venation. The accompanying figure of the vena- 

 tion of the house 

 fly (Fig. 79) indi- 

 cates the character 

 of this venation. 

 The only variation 

 o f m u c h signifi- 

 cance is the weak- 

 ening, or entire 

 suppression, of one 



or more of the posterior veins, or the posterior cross veins, in 

 the smaller species. This reduction process is carried to the 

 extreme in the Phoridie. In no case is there any difficulty 

 in recognizing the character of the remaining veins. 



The Pupiparia possess a venation which is evidently of the 

 same type as that of the last group. It lacks the cross veins, 

 but does not differ greatly from the wings of the Orthorapha 

 that have undergone this reduction. As far as the wings indi- 

 cate, there is little ground for making the Pupiparia a group 

 of as high rank as is usually done. 



There are three principal schemes of nomenclature for the 

 dipterous wing. One of these is that of the systematists, in 

 which the evident strong veins of an Orthoraphid wing are 

 numbered, from in front backward, first longitudinal, second, 

 etc. In the lower groups this is quite consistently followed, 

 the additional veins being usually treated as branches or as 

 added veins. In the reduced venation of the Cecidomyidte a 

 mistake was early made in the attempt at homologizing the 

 veins, and this error, though recognized, was held to for sake 

 of uniformity within the family. The terms, therefore, do not 

 have the same significance in that group as elsewhere. 



The scheme proposed by Adolph, and followed by Redten- 

 bacher, is the most elaborate attempt yet made to bring the 

 Diptera into line with other orders in vein nomenclature. 



