130 * DURHAM DIPTERA. 



XXIV. 



10 (7). V.6. very faint, male organs not prominent, arista 



almost terminal. Achalcus, Lw. (241) 



11 (6) (12). Acrostichal bristles in one row, or irregular ; 



antennae and abdomen mostly orange. 

 254. Bathycranium, Strobl. (1360. bicolorellus, Ztt.) 



12 (6) (11). Acrostichal bristles absent. 



13 (14). Bristles on the thorax and scutellum black, genital 



lamellae concealed; very small species, scarcely 

 i mm. 

 256. Micromorphus, Mik. (1362. albipes, Ztt.) 



14 (18). Bristles on the thorax and scutellum yellow, male 



organ a large swollen knob, dorsum with a deep 

 impression in front of the scutellum; at least 

 2 mm. Xanthochlorus, Lw. (253) 



15 (5). Metallic green or black species, veins never yellow. 



16 (43) (51). Acrostichal bristles in two rows. 



(Note. — Male organ prominent and bent under the abdomen (VI. 17) with scale- 

 like lamellae in paragraphs 17-34).- 



17 (20). Hind metatarsi with one or more bristles above in the 



male. 



18 (19). Jowls below the eyes conspicuous. 



Hygroceleuthes, Lw. (222) 



19 (18). Jowls very small below the eyes, practically absent. 



Dolichopus, Ltr. (223) 



20 (17). Hind metatarsi without any bristles above. 



21 (22). Jowls conspicuous, hind femora with a row of erect 



bristles in front. Tachytrechus, Stan. (224) 



22 (21). Jowls very small below the eyes, hind femora without 



the erect bristles in front. 



23 (40). Hind coxae with only one erect bristle outside. 



24 (85). Hind femora with a praeapical bristle. 



25 (32). 0.4 2 narrowed towards its end. 



26 (27). Arista distinctly hairy. Pcecilobothrus, Mik. (225) 



27 (26). Arista with a leaf-like expansion at the middle or 



end. Sybistroma, Mg. 



28 (31). Proboscis shorter than the head. 



29 (30). Male organ not stalked. Hercostomus, Lw. (226) 



