172 KANSAS UNIVERSITY SCIENCE BULLETIN. 



two subdorsal lines obscure yellow, one humeral, two post- 

 humeral, one presutural, two supraalar, one postalar, three 

 dorsocentrals, and a pair of small prescutellar bristles present ; 

 scutellum obscure yellow, brown on sides at base, with an apical 

 and a basal pair of bristles ; metanotum black ; halteres yel- 

 low ; pleurae obscure brown, one mesopleural and two sterno- 

 pleural bristles present. Legs yellowish brown, middle coxae 

 with several strong bristles, anterior femora with five long 

 bristles on posterior margin, middle and hind femora with a 

 row of six short, but strong, bristles on outer side of apical half, 

 preapical bristle of tibiie strong. Abdomen yellow, posterior 

 angles of first segment, posterior border of following segments, 

 a median vitta on the last three, and the hypopygium largely, 

 black. Wings hyaline, a spot at tip of first vein, one on small 

 cross- vein, two on second and third veins opposite hind cross- 

 vein, the one on the second vein is the larger, another one on 

 the third vein a little way from the tip, another opposite this 

 one on the fourth vein, and one on the hind cross-vein, brown ; 

 costa reaches tip of fourth vein, its third section about a third 

 as long as the second, and scarcely as long as the penultimate 

 section of the fourth vein. 



Female : Head and thorax yellow ; face and cheeks light yel- 

 low ; mesonotum with two subdorsal, brown vittse reaching 

 two-thirds way to posterior margin. Abdomen obscure yellow- 

 ish brown. Otherwise as in the male. Length, 4 mm, 



A specimen of each sex ; February and April. At first glance 

 one would not suspect that these two specimens represent the 

 same species ; but the form of the front, the antennae, face, 

 the chsetotaxy of the front, thorax, and legs, and the wings in 

 structure and markings, are identical. 



Pachycerina. 



(Macquart, Hist. Nat. Dipt. H. SU : 1835.) 



Pachycerina vaga, n. sp. 



Female : Close to P. seficornis Fall. Head yellow ; front 

 opaque, a little broader than one eye, with slightly divergent 

 sides, large ocellar dot opaque black, two fronto-orbitals, two 

 verticals, and a pair of bristles behind ocelli present, ocellar 

 bristles absent, minute light brown spot at base of each fronto- 

 orbital, a median brown line from ocelli to antenniB, where it 



