192 DIPTEBA. 



PROMACHUS. 



Promachus, Loew, Linn. Entom. iii. p. 390 (1848) . 



Except P. albifades, Willist., of which we have a considerable number of specimens,, 

 the other species of this genus are but poorly represented in the collections before me ;. 

 there are at most two specimens, in many cases only one, of each, and these are often 

 but indifferently preserved. Our species may be grouped as follows: — 



A. The red or yellow tibiae forming a marked contrast with the black femora. 

 Lateral and hind margins of the abdominal segments 2-5 greyish polli- 

 nose, the black on these segments forming a broad subquadrate patch; 

 the grey shadow in the submarginal cell long ; beard yellow ... 1. dnctus, Bell. 

 Lateral and hind margins of the abdominal segments 2-5 yellowish-grey 

 pollinose, the black patch on these segments having oblique sides, and 

 being semicircular, rather than subquadrate ; the grey shadow in the 



submarginal cell rather short ; beard greyish 2. sp. ? 



Lateral (not hind) margins of the abdominal segments greyish pollinose 3. forfex, sp. n. 

 AA. The colour of the tibiae not forming a marked contrast with that of the 

 femora. 

 Legs black ; first submarginal cell without grey shadow in the middle. 



The first two abdominal segments beset with soft white hair . . 4. anceps, sp. n. 

 The first two abdominal segments beset with soft yellow hair . . 5. sp.? 

 Legs not black ; first submarginal cell with a grey shadow in the middle. 

 The grey shadow very narrow ; the hairs on the cheeks and front 



coxae snow-white 6. albifades, WilL 



The grey shadow broad ; the hairs on the cheeks and front coxae 



yellow 7. nobilis, sp. n. 



The known species of Promachus from America north of Panama (those not found in 

 our region are bracketed) may be grouped as follows : — 



A. Male forceps with a tuft of silvery pile. 



[fitchii, O. S.], [princeps, Willist.], albifades, Willist., [bastardi, Macq.], truquii, Bell. 

 AA. Male forceps without tuft of silvery pile. 



[yertebratus, Say], [rufipes, Wiedem.], [fuscipennis, Macq.], ductus, Bell., quadratus, Bell. 

 (? = forfex, O. S.),pulchellus, Bell., trapezoidalis, Bell., nobilis, O. S., and sp. No. 5 of the 

 present work. 



Of the following species the female alone has been described : — magnus, Bell., anceps, 

 O. S. {\=.fuscipennis, Bell.), quadratus, Wiedem., and No. 2 of the present work. 



The description of P. quadratus in Wiedemann reads very much like that of P. bastardi, 

 Macq., $ ; nevertheless, Williston is right when he says that Schiner was acquainted 

 with the type of P. quadratus, and would hardly have redescribed it under the name of 



