24 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.61. 



POLYAULON COMPRESSUM, new species. 



" Diatora compressa Ashm. MS. n. sp.." Slosson, Ent. News, vol. 13, 1902, 

 p. 320. 



Runs to Polyaulon in Foerster's key to the Plectiscoidae and agrees 

 with the description except that the ovipositor is distinctly exserted 

 and the nervulus is interstitial. 



Female. — Length, 3 mm. ; antennae, 2 mm. 



Head polished, broad behind eyes, face siibopaqne, half as long as 

 broad; clypeus polished, sharply separated, two-thirds as long as 

 broad, somewhat compressed from sides, strongly rounded both 

 basally and apically; malar space much longer than basal width of 

 mandible and nearly half as long as eye ; ocelli very small, in a nearly 

 equilateral triangle; antennae rather slender, thicker toward apex, 

 flagellar joints strongly ridged longitudinally, first three times as 

 long as thick, those toward apex as thick as long; thorax compressed; 

 mesoscutum and scutellum polished ; pronotum and mesopleurum sub- 

 polished coriaceous; sternauli distinct anteriorly; metapleurum and 

 propodeum opaque coriaceous, petiolar area subpolished, areolation 

 complete, petiolar area occupying more than half dorsal length, areola 

 hexagonal ; legs, especially hind tibia, rather stout, hind legs long, 

 femora reaching beyond apex of third tergite; stigma narrow, radius 

 at its middle ; metacarpus two-thirds as long beyond radius as before ; 

 no trace of second intercubitus ; second recurrent curving strongly 

 toward apex of wing, its angle with subdiscoideus acute; discoidal 

 cell broad at apex, narrow at base, nervulus interstitial; nervellus 

 unbroken, reclivous; abdomen one and one-half times as long as head 

 and thorax, compressed from base of fourth tergite, first tergite 

 opaque, others polished; first tergite nearly three times as long as 

 wide at apex, postpetiole but little wider than petiole, spiracles 

 slightly behind middle, in profile arched above, straight beneath ; 

 second tergite nearly as long as first, slightly longer than wide at 

 apex ; third to fifth gradually shorter, others very short ; ovipositor 

 sheath nearly as long as first tergite. 



Black; mandibles and palpi pale; antennae at base and legs testa- 

 ceous ; abdomen beyond first tergite piceous ; wings hyaline, venation 

 brown. 



Type locality. — Alpine region of Mount Washington, New Hamp- 

 shire. 



Type.— Cat. No. 25029, U.S.N.M. 



One specimen taken by Mrs. Annie T. Slosson. 



The compression of the thorax and abdomen give this species an 

 appearance like the Orthocentrini, while the sternauli and narrow 

 first tergite are suggestive of the Hemitelini; but the compressed 

 clypeus and venation, notably the discoidal cell and nervellus, indi- 

 cate its Plectiscine affinities. 



