360 SUPPLEMENT. 



Abdomen green at the base, the black bauds increasing in width so that the tip is nearly all black ; the 

 hair on the segments long and black, and at the tip forming a straight tuft projecting backward and 

 downward, as in P. caudatus, the ends of these hairs being somewhat crimped. Hypopygium small, 

 imbedded ; the appendages are, however, prominent, curved, black organs, two in number, each with a 

 tuft of black hair at the tip ; there are two smaller inner organs, also black. Coxae and femora bright 

 green ; hind tibiae and tarsi black ; fore and middle tibiae and the tips of the femora yellow ; fore tibia? 

 and tarsi plain ; middle tibiae with a long thin spine on the inner side at the tip ; middle metatarsi 

 black, with short bent bristles, as in P. caudatus. Wings hyaline, venation as in the species mentioned. 

 The female is readily distinguished by the dark hair on the face. 

 Length 4-5 millim. 



Hob. Mexico, Amula, Xucumanatlan, and Chilpancingo in Guerroro (H. H. Smith). 

 — Beaztl, Rio Janeiro. 



This species is further distinguished from P. caudatus by the fact that the female 

 has the femora and fore coxae green, like the male. The Brazilian specimen was given 

 to me by Prof. Williston. 



17. .Psilopus caudatus. 



Psilopus caudatus, Wiedem. Aussereur. zweifl. Ins. ii. p. 224 \ 



Psilopus caudatulus, Loew, Neue Beitr. viii. p. 93 2 ; Mon. N. A. Dipt. ii. p. 271 3 . 



Hob. Noeth Ameeica 23 , New England to California \ — Mexico, Cuernavaca, Medellin, 

 Atoyac, Vera Cruz, Frontera, Teapa (H. H. Smith). — South Ameeica to Brazil. 



Numerous specimens. Loew seems to have laboured under some mistake, as he 

 says of P. caudatus : " By its larger size, it seems to be different from the species 

 known to me." Wiedemann mentions a length of 2-2J lines, Loew *15 inch ; there 

 is no great difference. The largest specimens in this collection measure -19 inch, just 

 the size of Wiedemann's. It is an exceedingly common and widespread species, 

 ranging north to New England and south to Brazil or farther. 



18. Psilopus nobilissimus, sp. n. (Tab. VI. fig. 28, s .) 



<3 . Face very broad, especially above, not much pollinose in any light, with a deep transverse impression 

 below the middle and a bulging prominence above this, extending into the lower part of the front ; 

 antennae entirely black, small, second joint with a few moderately stout bristles only ; arista subapical, 

 extremely stout at the base, about the length of the entire body, ending in a small, ovate, pointed 

 lamella. Front very bright green, wide, with numerous pale hairs. Thorax and abdomen bright blue or 

 green, with long bristles ; pleurae in the proper light with white pollen. Teguhe with long black cilia ; 

 halteres yellow, the stem more or less infuscated. Abdomen without black incisures ; the bristles 

 remarkably long. Hypopygium with the slender base purple, the middle black, the two joints of the 

 body of it with long, slender, wavy bristles extending downward ; the lamellae large, narrow, crooked, 

 pale yellow. Coxae and femora black, the fore and middle knees yellow; tibiae yellow, the hind ones 

 very slightly infuscated at the tip ; fore tibiae on the outer side with a row of about seven bristles of 

 increasing length, the last remarkably long and rather distant from the tip ; middle tibia? with a few 

 scattered small bristles, of which two or three on the outer side are of increasing size towards the tip ; 

 fore tarsi whitish, bare, the last joint a little infuscated, with a few flattened silvery hairs above ; middle 

 tarsi slender, infuscated from the middle of the third joint, the last two joints, however, somewhat 

 Avhitish, and on their upper surface thickly fringed with short silvery pile ; hind tarsi short, plain, black. 



