SYNOPSIS OF NORTH AMERICAN SYRPHIDiE. 225 



3. — Secoud and third jibdoniiual segments (at least) I'ed 4 



Second and third segments wholly black, or with yellow spots 7 



4. — Abdomen wholly red except the first segment; hind coxaj of the male withoiit a 



tooth below bicolor 



Abdomen except the first segment, not wholly red 5 



5. — Second abdominal segment with a basal black triangle; the 2-4 segments with 



narrow lateral black margins margihalis 



Abdomen not so marked 6 



6. — Hind coxie of -male with a spnr below flavitibia 



Hind cox;b of male without a spur below notha 



7. — Front and middle legs and a large part of the hind femora yellow ; large 



species 8 



Front legs in large part black 9 



8. — Coxai black curvipes 



Coxic yellow vec3rs 



9.— Abdomen long, slender, with two yellow spots on the second segment .... 



angustiventris 



Abdomen not unusually slender 10 



10. — Abdomen with two pairs of yellow spots 12 



Abdomen wholly black 11 



11. — Third joint of antenna? but little longer than broad . . Anthreas, obscura 



Third joint large, much longer than broad elongata 



12. — Hind femora much thickened, smaller species 13 



Hind femora moderately thickened 14 



13. — Arista wholly black nemoruni 



Arista yellow at the base fraudulosa 



14. — Fourth abdominal segment brilliant bronze; third longitudinal vein gently 



curved analis 



Fourth abdominal segment black ; third vein quite straight . . . ejuncida 

 For other species, see descriptions. 



Xylota (?) tuberans, n. sp. 



Eahitat.—Texiis ! 



(?. Leugtb, 9 to 10™'". Shining black. Face thickly gray jiollinose, 

 except on the tubercle ; occiput and posterior orbits densely pollinose. 

 Third joint of antenna? not large, orbicular ; thorax shining, thinly and 

 short yellowish and black pilose. Abdomen wholly shining black, 

 nearly bare. Legs black, all the tarsi, except the last two joints, yellow- 

 ish white. Hind femora thickened and elongate, not arcuate. Coxae 

 without spurs. Wings nearly hyaline toward the base, infuscated on 

 outer part. Stigma luteous. 



One specimen, Texas, National Museum. 



The present species cannot properly be placed in this genus. The 

 neuration is the same, except that the ci'oss-vein is not at all oblique. 

 The head in general structure is the same, but the face is very distinctly 

 tuberculate. In profile it is strongly concave below the antennse, then 

 forms a small but prominent tubercle opposite the lower border of the 

 eyes, and the face is more produced than in Xylota. The cheeks are 

 bioader and form an obtuse angle with the plane of the occiput. The 

 abdomen is elongate, but is much stouter and broader than in most 



