ZooL.— Vol. II.] WHEELER— DOLICHOPODID^. 7 1 



Four specimens of this little species were received from 

 Mr. C. W. Johnson. They were collected at Cape May, 

 N. J., June 6, 1891. 



Plagioneurus Loew. 

 71. Plagioneurus univittatus Loew. 



Plate IV, Fig. 105. 



Williston in a brief note ^ showed that Loew was mistaken 



in supposing the hypopygium of the male of this species to 



be disengaged. The only other generic character which 



Williston noted in his specimen is the slightly narrower face 



of the male. From a study of four male and four female 



specimens in my possession I am able to add the following 



details: — 



The third antennal joint is distinctly larger in the male; the white post- 

 ocular cilia and the white hairs on the fore coxae and on the lower surfaces of all 

 the femora are longer than they are in the female. The abdomen is laterally 

 compressed, of about equal height throughout, and appears truncated at the 

 end of the sixth segment because the small hypopygium is so completely 

 withdrawn. In one specimen I can make out the following details: the 

 sixth segment bears above on either side two macrochsetae, ventrally a tuft of 

 flattened black bristles. What I take to be the lamellae of the hypopygium 

 lie just below the tergum of the sixth segment. They are dusted with gray 

 and covered with long radiating white hairs. The inner appendages are 

 small and furnished on either side with three rather short black hooks. 



Plagioneurus univittatus is remarkable, first, because it is 

 the only species of a strongly marked genus, and secondly, 

 because it has an unusual geographical distribution. It 

 occurs in Brazil and Cuba according to Loew, in San 

 Domingo (Williston), Florida (C. W. Johnson)^ and in 

 the Middle States. I have taken it in Wisconsin and Illi- 

 nois from the beginning of July to the end of August, in 

 meadow-grass in company with Hygroceleuthus lati^es, 

 various species of Dolichopus, Pelastoneurus vagans, Scel- 

 lus exustus, etc. This very wide distribution, together with 

 the fact that only one species of this genus is known, 

 would seem to indicate that Plagioneurus univittatus is a 

 very ancient relict member of the Dolichopodidas. 



1 Dipterological Notes and Descriptions, p. 295. 



2 Proc. Acad. Nat. Sci., Phila., 1895, p. 320. 



