SYNOPSIS OF NORTH AMERICAN SYRPHIDiE. 143 



of the discal cell, aud the origin of the third veiu, with small indistinct 

 browish clouds; there are still smaller, almost imperceptible clouds at 

 the tip of the second veiu, near the junction with the first, and on the 

 curvature of the veiu closing the first posterior cell ; the latter section 

 of vein is more rounded here than in 2)usilla and fasciata; the marginal 

 cell is not quite so much expanded at its end ; anterior cross a little be- 

 fore the middle of the discal cell. 



Three specimens, Western Kansas and Colorado. 



Volucella tau. (Plate VI, lig. V.i.) 



Volucella tau Bigot, Aiinalcs Soc. Ent. de France, 1883, 84. 

 ir«&ito^.— California!, Mexico (Bigot). 



5,9. Length, 9 to 10""". Two male and one female specimens from 

 California, which agree with Mr. Bigot's description of a male from 

 Mexico, are very closely allied to Y. satur, yet are apparently different. 

 In all three specimens the spots on the wings are very distinct dark 

 brown, though small; the antennre are distinctly longer and more slen- 

 der (see figure). Mr. Coquillett, to whom I am indebted for the priv- 

 ilege of examining the specimens, has also compared a number more 

 with drawings of the antennje of both species which I sent him, and 

 finds the difference constant. The female has the markings of the ab- 

 domen nearly as in satur, that is with the black cross-bands entire; but 

 the male is very distinctly difterent. In this sex the black markings 

 are confined to the first segment, and an inverted t -shaped spot on the 

 second segment, the posterior black band being abbreviated a consider- 

 able distance before the lateral margin. The third and fourth seg- 

 ments have only an indistinct, somewhat brownish, color behind. The 

 hypopygium is black. 



Volucella obesa. (Plate V, tig. 9.) 



Syrjyhus obestis Fabricius., Syst. Ent., 763, o ; Ent. Syst., iv, 282 ; Syst. Antl., 227. 

 roluceUa obesfl Wiedemann, Auss. Zw. lQs.,ii, 199; Macquart, Hist. Nat. Dipt., i, 



494, :^. 

 OrnkJia ohem St. Fargeau aud Serville, Eocycl. Meth., x, 786. 

 ? Volucella azurea Phillipi, Verb. Zool. Bot. Geaell., 1865, 734, pi. xxvi, fig. 3.5. 



Rabifat. — Tropical regions (auct.), San Domingo, Mexico, Xew Mex- 

 ico I, Florida, (O. S.). 



S . Length, 9.5™"\ Brilliant shining green with violet reflections. 

 Antennae brown, third joint very short, subtriangular ; arista yellow, 

 black at tip, thickly plumose. Frontal triangle small, only a little swol- 

 len, T>ile black. Face a beautiful green with violet reflections in certain 

 lights, thinly pilose ; immediately below the antenute there is a large 

 white pollinose spot, and opposite it, near the eyes, a small one. In 

 profile the face is obtusely conical below, not descending far under 

 the eyes ; below the antennae rather deeply concave, near the middle 

 of the face with a large hemielliptical tubercle, and above it, on each 

 side, a somewhat smaller one, so that two distinct parallel grooves 



