1913] North American Dipterous Genus Nenrigona 23 



run a specimen through to the genus Neurigona. In most of 

 our species this is true but there are several exceptions. Dr. 

 Loew in his Monograph of the Dohchopodidas says that in the 

 South African species the third and fourth veins are parallel, 

 which is also the case with N. signifer Aldrich, and in one or 

 two of the species described in this paper. I might add that 

 the abdomen of the female is prolonged into more or less of an 

 ovipositor, as this character is of importance in separating this 

 genus from Xanthochlorus where the female abdomen is blunt 

 or rounded at the tip. 



Fred Kowarz in Wiener Entomoiogische Zeitung, II, p. 51, 

 uses the following characters in taking a specimen through to the 

 genus Neurigona: "Acrostichal bristles present, in two rows; 

 Arista dorsal; Fourth longitudinal vein not forked; hind coxae 

 with a single erect bristle on the outside; body color not 

 metallic." These characters hold good in all of the species 

 included in this paper that I have seen except that in N. albo- 

 spinosa n. sp. there are several weak and one stronger bristle on 

 the outside of the hind coxae; and the last character given would 

 have to be used in a qualified sense. 



There are a few characters which are common to most if not 

 all of our species: The lateral and lower orbital cilia are always 

 pale, as are also the cilia of the tegulae. The hind coxae have a 

 single large black bristle on the outside, except in albospinosa 

 n. sp. which has one large and several weaker whitish bristles 

 on the outside of the hind coxae. There are two large black 

 bristles on the margin of the scutellum, and in most of our 

 species there is a pair of weak bristles or hairs outside of these. 

 In all of our species that I have examined, and in the two 

 European species that I have seen, {4-fasciata Fab. and suturalis 

 Fall.), there are one or more pale yellowish bristles above the 

 front coxae; and often a black bristle on the middle and hind 

 trochanters. The hairs on the legs are arranged in longitudinal 

 rows, and the lower surface of the femora are usually bar?. 

 The males of many of our species have a ventral extension of 

 the fifth segment of the abdomen into which the hypopygium 

 partly fits when bent under the abdomen as it is ordinarily 

 carried, I have called these extensions sheaths, they are bilobed, 

 and form characters that can sometimes be used in separating 

 the species. 



