218 G. R. Osten Sacken: Diptera 



pes. Abdomen metallic greenish-black, reddish at the base, beset with 

 a fine golden pubescence. Front tarsi, and four last joints of the other 

 tarsi, dark brown. Halteres reddish. Wings tinged with brownish- 

 yellow; two dark brown crossbands cover the anterior and posterior 

 crossveins; both become evanescent posteriorly and merged into a broad, 

 gray, ill defined shadow along the posterior margin. The anterior 

 margin has a border of more intense yellow, which encroaches a little 

 beyond the third vein; about the middle of the wing it is abruptly cut 

 oflF; between the apex and the tip of the second vein there is a brown 

 margin, the proximal end of which comes in contact with the anterior 

 end of the brown crossband that passes over the posterior crossvein. 

 In some specimens this apical brown margin, as well as the crossband 

 connected with it, are much paler than in others; the other crossband, 

 or dark brown elongated spot, upon the anterior crossvein is usually 

 much darker. — Length 11 — 17 mm. Six specimens. — The eyes, 

 revived on wet sand, appeared purplish-greeu, without stripes, 



Xenaspis. 



0. Sacken, Bullet. Soc. Entom. Fr. 10. Aug. 1881. 



The most striking peculiarities of this genus consist: 1) In the 

 structure of the scutellum, which is merely a transverse swelling, pro- 

 jecting very little; 2) in the shape of the abdomen, the elongated first 

 segment of which is much narrower than the others. The shape of 

 the second basal cell is also very peculiar, but, as I will show below, 

 does not seem to be an altogether constant character. 



Head a little broader than the thorax, the profile projecting in 

 front of the eyes; lower occipital orbits moderately swollen, the upper 

 part of the occiput flat, falling off" perpendicularly behind the sharp 

 edge of the vertex. Face slightly concave, although very little re- 

 treating (in the profile); viewed in front, it is narrower above than 

 below; antennal foveae divergent, with wellmarked edges; a very narrow 

 orbit between them and the eyes; the triangular interval between the 

 foveae smooth, transversely concave. Oral opening large, nearly 

 circular; clypeus moderately broad; peristomium almost imperceptibly 

 arched in front, but much more behind ; palpi elongated, flattened. 

 Front broad with nearly parallel sides, turgid above the lunula; the 

 latter occupies more than half of the distance from eye to eye. Ocelli 

 not far from the edge of the vertex. 



Bristles; two pairs of vertical bristles of moderate size; no other 

 bristle on the head, except a small one on the check, near the pe- 

 ristomium, perceptible with some difficulty among a small tuft of 

 short hairs. 



