253 NORTH AMERICAN TRYPETINA. 



Observation 1. — The appended figure of the wing is taken from 

 a Mexican specimen. The specimens which I received from New- 

 York differ from the former in being a little larger and in the 

 circumstance that the face is somewhat more uneven ; perhaps 

 only in consequence of a stronger desiccation. Moreover, the last 

 section of the fourth vein is a little less curved, and the posterior 

 end of the first crossband is prolonged further along the margin 

 towards the posterior corner of the wing. In all other respects 

 the agreement is such that I cannot believe T. atra to be a 

 different species. From T. polita the present species is easily 

 distinguished by the much greater divergency of the second and 

 third crossbands on the wings, by the absence of the pale gray 

 border of the crossbands, which is always perceptible in T. polita, 

 and by the black coloring of the femora ; moreover, the anterior 

 part of the lateral border of the front bears only two bristles in 

 T. atra, while there are three in T. polita. The Brazilian species 

 T. nigerrima Loew is very much like T. atra, nevertheless they 

 are easily distinguished. In order to facilitate the comparison, I 

 let the description of this species follow. 



T. nigerrima Loew. $. (Tab. XI, f. 18.) — Atra, nitida, scutello 

 tumido concolore, thoracis maculis lateralibus utrinque binis velutinis, 

 abdomine fasciis albido-pollinosis ornato, capite flavo, pedibus ex-fer- 

 rugineo luteis, femoribus tamen posterioribus anticorumque litura ex- 

 fusco nigris ; alae albido-hyalinae, macula basali atra, fasciisque tribus 

 fusco-atris, prima latissima, reliquis minus latis, venis trausversis 

 valde approximatis. 



Deep black, shining ; the tumid scutellum concolorous ; thoracic dorsum 

 with two velvet black spots on each side ; abdomen with crossbands 

 of white pollen; head yellow; feet brownish-yellow, the posterior 

 femora and a stripe on the front femora brownish-black ; wings whitish- 

 hyaline with a deep black spot on the basis and with three black 

 crossbands, the first of which is very broad, the two others less so ; 

 crossveins very much approximated. Long. corp. 0.12 — 0.13 ; long. al. 

 0.12-0.13. 



Syn. Trypeta nigerrima Loew, Berl. Ent. Zeitschr. VI, p. 219. 

 Trypeta nigerrima Loew, Dipt. Amer. Sept. Cent. II, p. 89. 



Shining black. Head whitish-yellow ; the rather narrow and steep front 

 much darker yellow ; the frontal bristles black. Antennae dark yellow, 

 rather large, especially the elongated third joint, which has a rather sharp 

 anterior corner. Arista apparently bare, rather slender, not incrassated 

 towards its root, of a pale color. Fade but very little excavated, and very 



