266 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.45. 



9. Front between the antennal furrows with a broad, shallow depression. erraws, p. 269 

 Front between the antennal furrows convex or flat 10 



10. Scutellum with strong impressed median line brunneiceps, p. 269 



Scutellum without an impressed median line 11 



11. Postocellar line subequal with the ocelloccipital liae dissimilis, p. 270 



Postocellar line shorter than the ocelloccipital line 12 



12. Ovipositor color of the abdomen; body shining, finely granular. . .slossonx, p. 270 

 Ovipositor paler than the abdomen; body opaque, coarsely granular. 



nevadensis, p. 271 



13. Antennal furrows obsolete dorsally 14 



Antennal furrows complete to the ocelli 19 



14. Clypeus with a large, sharp, triangularly shaped tooth 15 



Clypeus without a large, sharp, triangularly shaped tooth 16 



15. Legs yellow; body variegated with black and yellow pint, p. 267 



Femora black; body black alni, p. 268 



16. Clypeus without a tubercule salids, p. 266 



Clypeus with a tubercule 17 



17. Body and legs ferruginous similis, p. 271 



Femora dusky black or black variegated with yellow 18 



18. Hypopygidium regularly tapering to the apex minor, p. 269 



Hypopygidium with the sides gently concave bakeri, p. 267 



19. Clypeus with a large, sharp, triangularly shaped tooth 20 



Clypeus without a large, sharp, triangularly shaped tooth 21 



20. Hypopygidium broadly rounded pini, p. 267 



Hypopygidium narrowly rounded luteopicta, p. 269 



21. Clypeus truncate or nearly so californica, p. 272 



Clypeus with a low median tooth 22 



22. Middle fovea obsolete slossonse, p. 270 



Middle fovea indicated 23 



23. Transverse median of the fore wings received in the middle of the first dis- 



coidal cell minor, p. 269 



Transverse median of the fore wings received beyond the middle of the first 

 discoidal cell coloradensis, p. 272 



XYELA SALICIS, new species. 



Female. — Length to the apex of the abdomen 3 mm.; length of the 

 ovipositor 1.5 mm. Clypeus not carinate; anterior margin broadly- 

 rounded; supraclypeal area convex; middle fovea obsolete; antennal 

 furrows obsolete dorsally; beliind each lateral ocellus is a faint 

 depression; postocellar furrow obsolete; postocellar line slightly 

 longer than the ocelloccipital Ime; head and thorax opaque, finely 

 granular; fourth and fifth antennal joints subequal, scutellum not 

 impressed; stigma sharply obHque on the first transverse radius, 

 about twice as long as its greatest width; sheath straight below, 

 straight above until near the apex when it is sharply oblique. Black ; 

 antennae, palpi, the femora beneath, tibise and tarsi and sheath 

 piceous; wings hyaline, iridescent; venation pale brown. 



Male. — ^Length 2.75 mm. Clypeus without a tubercule or a 

 carina, anterior margin nearly tnmcate, very slightly produced in 

 the middle; supraclypeal area convex; middle fovea obsolete; 



