38 OHIO STATK ACADKMY OF SCIENCE). 



margin, posterior branch of the fifth vein margined with brown which 

 color spreads across the apex of the anal cell and also unites with the 

 cross band across a large part of the fifth posterior cell, the apical spot 

 unites with the cross band in the marginal and first submarginal cells and 

 entirely fills them out with brown and extends into the anterior part of 

 the second submarginal. 



Female : The facial callosities black produced forward and inward 

 and meeting above the mouth, frontal callosity shining black; first two 

 segments of the abdomen broadly yellow on the sides, first segment dor- 

 sally with a large black spot beneath the scutellum, second with a black 

 spot which is variable in different specimens, in some it is smaller and 

 confined to the anterior half of the segment, while in others it is larger, 

 widened anteriorly, and may unite with the black of the third segment, 

 a transverse spot on anterior part of third segment occupying nearly its 

 whole width, last three segments black with yellow hind margins, ven- 

 trally abdomen yellow with small black spots in the middle of some 

 or all the first four segments, last three segments blackish with yellow 

 hind margins. 



Male: Abdomen, dorsally, yellow on the side of the first four seg- 

 ments, middle of each of these segments with a large black spot which 

 is widest before and which does not reach the posterior margin of its 

 segment except on the first where it is confluent posteriorly with the 

 black of the second, last three segments black with yellow hind margins, 

 ventrally, like the female except the black markings are larger than in 

 that sex. 



Habitat : Sandusky, Ohio. 



Chrysops frigidus is the only North American species of its 

 genus so far described with an apical spot and with the face en- 

 tirely black in ground color. In other species of its group the 

 ground color above the mouth is yellow. In this particular it 

 agrees with C. celer and other members of the group without an 

 apical spot. 



CHRYSOPS INDUS Ostcn Sackcu. 



Length 7-9 mm. The apical spot fills out the marginal and first sub- 

 marginal cells, and extends into the second submarginal along the apical 

 three-fourths of the anterior branch of the third vein. 



Female: Frontal callosity black, face, palpi and base of antennae 

 yellow ; first basal cell of the wing brown except a small patch in the 

 apical third ; abdominal segments one to four and oftentimes five and 

 six yellow on the sides ; yellow triangles on the middle of the third and 

 following segments produced forward and dividing the black of these seg- 

 ments into two parts, thus a middorsal line is formed composed of a series 

 of triangles ; there is a conspicuous triangle on the second segment but 

 it does not extend forward to the anterior margin of that segment. 



Male : Much darker in color than the female ; usually the first basal 

 cell is entirely filled out with brown, but in all specimens I have seen 

 there is a small hyaline patch at the apex of the second submarginal cell 

 and in some specimens a very small hyaline patch is present in the apical 

 third of the first submarginal : anal cell entirely infuscated ; abdominal 

 segments one to four narrowly margined with yellowish on the sides ; 

 posterior margins of the segments behind the second narrowly but plainly 

 yellow, and second and following segments with very small yellow tri- 

 angles ; abdomen otherwise clear black. This sex is here described for the 

 first time. 



