260 NORTH AMERICAN TRYPETINA. 



Observation 2. — T. polita and atra, as well as T. nigerrima 

 are closely related in their organization. Among the European 

 Trypetde, the species of the genus Oedaspis stand next to them, 

 especially when this genus is confined to Oedaspis multifasciata 

 Loew and its next congeners, at the exclusion of Oed. Wiede- 

 manni Meig. and vesuviana Costa. The American species differ 

 from the above-mentioned European ones (multifasciata Lw., 

 dichotoma Lw., and fissa Loew) in several characters, which they 

 have in common; the most striking of these are: 1. The rather 

 long, stubble-shaped pile ; 2. The longer and more pointed ovi- 

 positor ; 3. The different picture of the wings. The latter differ- 

 ence will be sufficiently apparent, when the figures which I give 

 of the wings of polita, atra, and nigerrima are compared with 

 the figures of the wing of T. multifasciata, produced in the 

 Europ. Bohrfliegen, Tab. YI, f. 2. The pictures of T. fissa and 

 dichotoma agree, in their general features, with that of multi- 

 fasciata. These differences of the three North American species 

 are not of sufficient importance to require the establishment of a 

 new genus for them, and I have not the slightest hesitation in 

 placing them in the genus Oedaspis, in the narrower sense, 

 defined above. 



22. T. gib"ba n. sp. 9 • — Atra, nitida, scutello tumido, concolore, facie 

 albicante, pedibus subbadiis ; alae albido-hyalinse, inaculS, basali atnl 

 fasciisque tribus latis fusco-atris, venis transversis valde approximatis, 

 cellula marginali per venulam transversalem adventitiam dissecta. 



Deep black, shining; the turgid scutellum of the same color; face 

 whitish ; feet chestnut-brownish ; wings whitish-hyaline, with a deep 

 black spot at the basis, and with three brownish-black crossbands, very 

 much approximated crossveins, and a supernumerary crossvein dividing 

 the marginal cell. Long. corp. 0.13, cum terebra 0.17 ; long. al. 0.14 

 —0.15. 



"Very like the three preceding species and closely allied to them, 

 nevertheless, distinguished in some peculiar plastic characters. 

 Deep black, shining. Front conspicuously broad, of an opaque, 

 dirty, brownish, more reddish-brown on the sides ; the four 

 bristles on the posterior part of the vertex, the bristles near the 

 ocelli, the four bristles crowded together and inserted on the small 

 stripes running from the vertex towards the front, finally two 

 bristles on each side, near the lateral frontal border, are all black; 

 the latter two are inserted, one very high up, the other very low 



