OSTEN SACKEN ON WESTERN DIPTERA. 339 



Legs black ; knees and base of tibiae of the two anterior pairs pale 

 brownish; hind femora somewhat incrassate and beset with a tuffc of 

 yellow hairs above ; hind tibiae rather stout. Wings tinged with red- 

 dish-brown anteriorly, especially along the veins, the inside of the cells 

 being paler; posterior portion subhyaline, slightly brownish along the 

 veins. 



Rab. — Marin County, California (H. Edwards). A single female. 



Observation. — If a face prolonged downward, and provided with a 

 tubercle in the middle, is to be considered as characteristics of Crior- 

 rhina, the present species and the following do not belong in that genus. 

 In both of these species, the face forms a short snout, prolonged ante- 

 riorly rather than downward, somewhat obtusely keel-shaped above, 

 and deeply emarginate at the tip. There is no tubercle on the face, which 

 is in thft profile gently concave between the antennas and the oral edge. 

 The hind femora are stouter than in Griorrhina, especially a short dis- 

 tance before the tip. As these species have no spines on the under side 

 of the hind femora, and as the palpi are rather long and narrow, they 

 cannot be placed in the genus Brachy palpus. The great looseness with 

 which most of the genera of Syrphidce are defined makes me very little 

 inclined to increase their number without absolute necessity. I prefer, 

 therefore, to place these species provisionally in the genus Pocota, adopted 

 by St. Fargeau and resuscitated by Schiner, the face of which is without 

 tubercle, although, judging from the description, it has a somewhat dif- 

 ferent structure. I will observe here, at the same time, that Schiner 

 calls the genus Plocuta, while I find Pocotain the Encyclopedic Methodique, 

 probably from fcdxoq, sheep-wool ; ttoxow, to cover with wool. 



Pocota cyanella n. sp. — Thorax greenish-black, beset with long, 

 grayish pile above, and yellowish-white pile on the sides ; abdomen dark 

 bluish-metallic ; in the male with a black, opaque second segment, and a 

 black, opaque cross-band on the third ; legs black. Length 9-lG mm . 



Face black, shining ; snout projecting, keel-shaped above ; on each 

 side of the snout, a broad stripe of grayish pollen somewhat conceals the 

 black ground-color ; front and vertex black, but little shining in the 

 female, and densely clothed with yellowish- white pile, some of which 

 descends along the sides of the face, below the antennas ; the occiput 

 and the posterior and inferior orbits of the eyes are beset with pile of the 

 same color. Antennas brown ; first joint paler; arista reddish. Thorax 

 metallic greenish-black, densely clothed with pile, which is of a dull- 

 grayish on the dorsum and more yellowish- white on the pleurae. Halte- 

 res brownish. Abdomen dark metallic-blue, beset, especially on the 

 sides, with whitish pile ; in the male, the second segment is black, opaque, 

 except two triangles on each side, which are metallic-blue ; the third 

 segment has an arcuated, black, opaque cross-band, somewhat inter- 

 rupted in the middle. Legs black ; tibiae brown; knees of the two first 

 pairs yellowish-brown ; the legs are beset with whitish pile, which is 

 longer on the femora, short on the tibiae ; hind femora somewhat in- 



