214 Annals Entomological Society of America [Vol. XIII, 



along the posterior margin. All the rest of the segments have 

 marginal bristles, those at the sides being longer and stronger 

 than those near the median line. The ventral plates have only 

 a few bristles at the margins and a sparse covering of hair 

 towards the center. (Figs. 37 and 40). The first genital seg- 

 ment in the male has several long, strong bristles, while the 

 second has a few along the posterior border. The forceps (fc) 

 each have a distinct spur or tooth near the tip, and are covered 

 with short bristles. The apical point of the second genital seg- 

 ment has two long, weak bristles (Fig. 37). The genital seg- 

 ment in the female has only a few short bristles on the ventral 

 side (Fig. 40). 



The chaetotaxy of the abdomen is not constant, and the 

 number of marginal bristles varies with the individual. 



SUMMARY. 



The head, with the exception of the face, the epicephalon 

 and metacephalon, is apparently all one piece, divided into 

 regions which are constant for both sexes. With the exception 

 of the face, the anterior portion of the head is one piece, divided 

 into distinct regions. 



The chaetotaxy of the head is constant for each sex and can 

 be relied upon. 



The thoracic sclerites in the two sexes are the same, and are 

 constant. 



The bristles of the mesonotum are constant with the excep- 

 tion of the weak acrostichal bristles which vary in number and 

 arrangement. 



The males are always equipped with three sternopleural 

 bristles while the females have only two. 



The hair covering of the pleural sclerites is the same in 

 both, but not regular. 



The third and fourth veins of the wings are either parallel 

 or diverging at the tip, never converging, while the anterior 

 cross vein is never perpendicular to the fourth vein, meeting the 

 discal cell at its distal third. 



The bristles of the legs are constant in location, but not in 

 number, and an apical spur is present on all the tibia. 



The abdomen has five segments, and one or two genital 

 segments. The chaetotaxy is not constant. 



