24 PROCEEDINGS OF THE NATIONAL MUSEUM vol.68 



femur without anteroventral comb; fore and hind tibiae with very 

 short preapical bristle. Inner cross vein at middle of discal cell, 

 outer at less than its own length from apex of fifth vein; last sec- 

 tion of fourth vein three times as long as preceding section. 



Length, 3.5 mm. 



Type. — Barro Colorado, Panama Canal Zone, July 1, 1923 (R. C. 

 Shannon). Cat. No. 28457, U.S.N.M. 



The shining black thoracic dorsum and yellow legs with black 

 tipped femora readily distinguish this from any known species of 

 the genus. 



Subfamily Periscelinae 



This subfamily, as mentioned under the family discussion, is dis- 

 tinguished by the presence of but one orbital bristle, the divergent 

 postvertical bristles, and the incomplete auxiliary vein of the wings. 



So far only one of the genera has been recorded from the Old 

 World but all four occur on this side of the Atlantic. 



KEY TO GENERA 



1. Auxiliary vein without indication of a forward bend at apex ; face 



conspicuously protruded below 2 



Auxiliary vein with a distinct forward cuiwature at apex; face not 

 conspicuously protruded below 3 



2. Face conspicuously flattened, more or less shield shaped below antennae, 



the flat part bare, sides hairy Scutops Coquillett. 



Face evenly convex, entire surface hairy Neoscutops, new genus. 



3. Face flattened but not conically pi'oduced below ; space between bases of 



antennae about as wide as that between either antenna and eye; frons 

 much over half of the head width ; vibrissae small but distinct. 



Sphyraperiscelis Sturtevant. 

 Face not flattened ; space between bases of antennae linear ; frons about 

 half the head width ; vibrissae not dcA'eloped Periscelis Loew. 



SCUTOPS FASCIPENNIS Coquillett 



This species appears to be not uncommon in Costa Rica from 

 whence I have seen some specimens collected by P. Schild. 



I have figured the head (fig. 5) and the wing (fig. 3) of this species 

 to show the distinction between it and the new species included in 

 this paper. 



SCUTOPS MACULIPENNIS, new species 



Male and fem<ile. — Head yelloAvish white, with gray pruinescence, 

 frons with a large black mark extending from vertex to beyond 

 orbital bristle on each side, the triangle fuscous; face with a dark 

 median stripe which has lateral branches about middle and is dilated 

 at apex of the flattened ai'ea, below the latter there is a transverse 

 black stripe from eye to eye ; antennae whitish, second segment black, 

 third darkened above; palpi broadly black at apices. Thorax black, 

 dorsum with dense grey pruinescent markings as in figure 6, hii- 



