350 SUPPLEMENT. 



coxae, pale yellow, hind tarsi only very slightly infuscated at the tip ; hind metatarsi shorter than the 

 following joint, on the underside with one or two oblique rows of comb-like spinules (not perceptible 

 except under a high power) ; hind coxae with one erect bristle on the outer side. Wings hyaline, broad ; 

 the second and third veins far apart at their tips. 

 Length 1 millim. 



Hab. Mexico, Teapa in Tabasco (H H Smith). 



A single male. A female, from Medellin, near Vera Cruz, differs in the following 

 particulars : it is larger, the bristles are paler, and the minute brown ovipositor 

 protrudes in a triangular form, this portion being reddish-brown in colour, with 

 perceptible dentations on the edges ; the purple face, front, and thoracic dorsum are 

 as in the male. Length 1*5 millim. 



A second male, from Medellin, has the thorax wholly golden-green, the antenna? 

 acorn-coloured, and the abdomen bright green; I doubt if it belongs to the same 

 species. 



The members of this genus, on account of the extreme delicacy and softness of the 

 integument, are probably subject to even more variation in the hues of blue, green, 

 and violet than other Dolichopodidae. For the purposes of classification it is very 

 essential that they should be observed while fresh, and in large numbers. To judge 

 from the material before me, it seems probable that Thrypticus is fairly rich in species. 



4. Thrypticus (?) ? 



Hab. Mexico, Omilteme (H. H. Smith). 



A male and two females from Omilteme seem to belong near Thrypticus. The 

 hypopygium is more compact and bulky than in that genus, the arista is distinctly 

 dorsal, and there are no acrostichal bristles, except a few in one female, which may on 

 that account belong to a different species, though otherwise indistinguishable. 



PSILOPUS (p. 214). 



The American species of Psilopus have received no general treatment, except from 

 Loew, and his work was confined to North- American forms, chiefly, indeed, to those of 

 the United States, as he had but little material from other parts. The great number 

 of descriptions of the earlier writers has been an obstacle to any advancement in the 

 study of the genus, since very few of these refer to characters that are really distinctive. 

 The course I have followed, which appeared to be the only one possible, has been to 

 examine all the old descriptions, arrange the specimens at hand, construct a Table of 

 all recognized North, Central, and South-American species, and describe as new all 

 those that could not be identified. The Table includes forty-seven species, all of which 

 are known to me, except P. pilosus, Loew. The male of P. basilaris remains 

 unidentified, but the female is readily recognizable, unlike many of the genus. In 



