1913] North American Dipterous Genus Neiirigona 31 



bristles on the middle coxae; dimidiata also has pale hairs on 

 most of the first four segments of the abdomen while in this 

 species they are mostly black, the front of the wing in this 

 species is also more arched. 



3 Neurigona dimidiata Loew. 



Figure 3. 

 Saucropus dimidiata Loew, Neue Beitr., viii, p. 75, 1861; Mon. N. A. Diptera, 

 ii, p. 225, 1864. 



Thorax and abdomen yellow, the former with the flattened space 

 and sometimes a central line black, the latter with black bands; 

 bristles and hairs of the front and middle coxse all yellowish; front 

 metatarsi about the same length as their tibiffi. Length 4 mm. 



Male: Eyes almost touching on the middle of the face; face and 

 palpi silvery white; proboscis and antennae yellow, arista brownish; 

 front and occiput black, thickly white pollenose, the pollen on the 

 occiput, the flattened space before the scutellum, and the metanotum 

 appears to be tinged with blue; orbital cilia whitish. Thorax yellow, 

 reddish yellow and shining on the dorsum, white pollenose on the pleurae, 

 there is the usual small black spot on the pleurae in front of the halters; 

 the flattened space on the dorsum black, and a black central line extends 

 from this to the front of the thorax between the acrostichal bristles, 

 this line seems to be a variable character, in one of the specimens before 

 me it is almost wanting; humeri yellowish white; metanotum black; 

 scutellum yellow, lighter colored on the disk and somewhat shining. 

 Abdomen yellow with rather narrow black bands on the second, third, 

 and fourth segments, those on the third and fourth sometimes not very 

 sharply defined; the hairs of the abdomen mostly yellowish, the marginal 

 row of bristles on the first segment black and rather short; fourth seg- 

 ment produced on the venter on the posterior end ; fifth segment higher 

 than long, somewhat pointed in front on the dorsum, entirely yellow except 

 the brown ventral sheath, and with rather long yellow hair. Hypopygium 

 black or testaceous, polished, and rather small with yellowish append- 

 ages. Legs pale yellow; front and middle coxae with all the hairs and 

 bristles yellowish white; hind trochanters with a small black bristle; 

 front tarsi more than twice the length of their tibiae, and with a row of 

 long hairs below ; front metatarsi a little longer than their tibiae ; middle 

 metatarsi about the same length as their tibiae; hind tarsi a little 

 shorter than their tibiae, first joint a very little shorter than the second ; 

 all the tarsi infuscated frcm the tip of the first joint. Wings hyaline, 

 very slightly tinged with grayish; the bend in the fourth vein rather 

 sharp and at the middle of the last section ; tip of the fourth vein before 

 the apex of the wing; posterior cross-vein a little less than twice its 

 length from the wing margin, measured on the fifth vein. 



Female : A single female that I take to be the female of this species 

 has black hairs and bristles on the middle coxae, and black bristles and 

 yellow hairs on the front coxae'; the front tarsi twice as long as their 

 tibiae, the metatarsi being as long as the tibiae; middle metatarsi as long 

 as their tibiae; first and second joints of hind tarsi equal. 



