300 Professor Williston on the 



closely set together ; style distinctly differentiated, and extending 

 at an angle with the third joint ; its first joint small ; second joint 

 thickened, spindle-shaped, finely and densely hairy, terminating in 

 a slender bristle about as long as the thickened portion of the 

 style ; altogether, the style is shorter than the third antennal 

 joint. Thorax shining metallic, deep green, with bine reflections 

 and erect black pile. Abdomen elongated, of equal width, black 

 or brownish black, the second, third, and fourth segments with a 

 narrow posterior margin of golden or silvery pubescence, forming 

 an interrupted band. Femora black ; tibiae light yellow with a 

 broad brown ring beyond the middle ; the hind pair with the 

 distal two-thirds brown ; tarsi light yellow or yellowish- white, the 

 distal three joints of the four anterior ones, the tip of the meta- 

 tarsi, and the remaining joints brown or brownish. Wings hyaline 

 on the basal anterior portion ; clouded behind, and blackish on the 

 outer half. Length 9 mm. 



Two males and oae female. The female diflfers in being* 

 of a larger size (12 mm.) in the absence of metallic 

 coloration, in tbe more reddish-brown colour of the 

 abdomen, and in the lighter coloured wings. It may be 

 an immature specimen. I at first identified this genus 

 as Ghromatopoda, Brauer, but it will be at once distin- 

 guished by the structure of the second antennal joint. 



AOCHLETUS. 



Osten Sacken, Biol. Centr. Amer. Dipt., 38, i., 1883. 



$ . Holoptic, the upper eye-facets moderately enlarged and 

 sharply distinguished from those of the lower portion. Antenna) 

 situated a little below the middle of the eyes in profile, shorter 

 than the head ; annuli of the third joint closely united, the first 

 one small and short, the sixth elongate and with several minute 

 bristles at the tip. Scutellum with two slender spines. Abdomen 

 slender, composed of five segments. Veins of the wings on the 

 outer posterior part weak or evanescent, the beginning of the 

 second and fourth ones arising from the discal cell apparent, 

 the first and third only faintly indicated by folds. 



1. Aochletus hidriatuSy n. sp. (PI. X., fig. 76, antenna.) 



$ . Face black, moderately shining ; on either side silvery 

 pubescent. Antennae black ; the first and second joints, for the 

 greater part, reddish. Mesonotum black, moderately shining ; 



