DTJKHAM DIPTEKA. 369 



LI. 637. 



45 (2). Antennae wholly yellow. 



46 (51) (52). Vertex with two black spots. 



47 (48). Arista pale with the base black. (geminata, Mg.) 



48 (47). Arista all pale or white. 



49 (50). Abdomen with four dark bands; arista pale; dorsum 



with red stripes. ( 2 7°9- rufina, Ztt.) 



50 (49). Abdomen with three dark bands ; arista white. 



(citrinella, Ztt.) 



51 (46) (52). Vertex with one black spot or triangle. 



51a (51b). Vertical triangle well separated from both eyes 

 and occiput, and with two pale spots, sometimes 

 reduced to a black ocellar spot. {pallefis, Lw.) 



51b (51a). Vertex with a large all-black triangle. 



(figurata, Ztt.) 



52 (46) (51). Vertical triangle shining orange, sometimes 



black-edged. 

 52a (52b). Abdomen with a central stripe; vertical triangle 

 with the edges and central line black; eyes large. 



(divisa, Lw.) 

 52b (52a). Abdomen entirely yellow, except two black basal 



spots. 

 52c (52d). Head larger than usual; vertical triangle with a 

 black spot at its fore corner. (binotata, Lw.) 



52d (52c). Head of the usual size ; no black spot at the fore 

 corner of the vertical triangle. 



271 1. Chlorops gracilis, Mg. 

 Hesleden, i ?, August, 1901. 



53 (1). Dorsum wholly black, or at most with the margin 



narrowly yellow. 



54 (59). Scutellum partly or wholly yellow. 



55 (56). Antennas orange with the third joint black above and 



at the point. 



2693. Centor cereris, Fin. 

 Bishop Auckland, 1 $, July, 1900. 



56 (55). Antennae wholly black. 



