DIPTEEA 



NORTH AMERICA 



PARTJT 



ON THE NORTH AMERICAN TIPULIDiE. 



(Part First.) 

 INTRODUCTION. 



1. Characters of the family. 



The Tipulidse belong in the number of those large families 

 of Diptera, the limits of which are equally well defined on all 

 sides. In the Dolichopodidse and Asilidse we have instances of 

 families of the same kind, and the words of Mr. Loew about the 

 latter " that not a single dipteron has yet been found, the posi- 

 tion of which as belonging or not belonging to this family is 

 questionable" — these words may, with almost equal propriety, be 

 applied to the Tipulidse. 



The presence of a transverse Y-shaped suture across the meso- 

 notum, would alone be sufficient to distinguish the Tipulidse from 

 the neighboring families. The completeness of the venation and 

 the structure of the ovipositor of the female are of equally general 

 application. Through the whole family, and all the modifications 

 in the other organs notwithstanding, the venation is arranged 

 according to the same plan, the characteristic features of which 

 are, the great length of the two basal cells, the development of 

 the auxiliary vein, and the presence, in the majority of cases, of 

 a discal cell. The veins, in their last subdivisions along the 

 margin of the wing, are from ten to twelve in number (if Clado- 

 1 May, 1308. /M 



