50 DIPTERA OF NORTH AMERICA. [PART III. 



consists of an infuscation of the stigma and of a black spot on 

 the apex. 



Cephalia is immediately connected with a genus embracing 

 Trypeta flexa Wied. and the genera related to the latter. As 

 this genus does not coincide with any one of the hitherto adopted 

 genera, it must receive a new name. I call it Tritoxa, the name 

 alluding to the peculiar picture of the wings. The Tritoxse 

 differ from the Cephalise in the presence of a strong bristle before 

 the end of the fore tibiae, on their upper side, and in the presence 

 of a weak indication of antennal foveas, especially, however, in 

 the fact that the third and fourth longitudinal veins have an 

 irregular course, in consequence of which the anterior basal cell 

 is expanded before its end ; moreover also in the first longitudinal 

 vein being, to a great extent, covered with bristles and in the 

 approximation of both crossveins to each other. The wings have 

 a dark coloring and the picture consists of three oblique, more 

 or less arcuated, hyaline crossbands. The other characters the 

 genus Tritoxa shares with the genus Cephalia. 



After Tritoxa Camptoneura naturally follows. The typical 

 species is the well-known North American species, described by 

 Fabricius as Musca picta, and afterwards erroneously placed by 

 Wiedemann in the genus Trypeta. Rob. Desvoidy was the first 

 to found a new genus for it, which he called Delphinia; Macquart 

 established later for the same species the genus Camptoneura, 

 which thus coincides with Delphinia. As the name Delphinia 

 cannot be retained for reasons of priority, Macquart's name must 

 be adopted. Camptoneura differs from Tritoxa in a striking 

 manner in the structure of the wings ; they are broad, and show, 

 on the costal margin, near the end of the auxiliary vein, a shallow, 

 but very striking excision ; the third longitudinal vein is very 

 remarkably sinuate, and the anal cell rounded at the end. The 

 picture of the wings has a distant resemblance to that of the 

 species of Aciura. 



The other genera of Cephalina which I know of contain 

 species of a less slender stature than the three genera which I 

 have just examined. 



Among them the genus Piara, founded by me for an African 

 species, is remarkable for its close relationship to the Platysto- 

 mina. It may be characterized as follows: — 



