SOUTH AMERICAN DIPTERA. 255 



rior orbits as somewhat swollen. In my male specimen they are but 

 very little so. In this female the posterior orbits are peculiarly en- 

 larged and thinned, so as to fit over the front margin of the thorax. 

 Altogether, this species, a true Myxosargiis, and though closely 

 allied to the type species, is, I believe, entitled to a name, which I 

 choose in honor of the talented author of the genus. The \vings 

 have the same pattern of coloration as in faseiatus, but the markings 

 are darker than in my specimen of that species. Three specimens, 

 Chapada. 



27. Chordonota nigra n. sp. 



% ■ — Length 5\ mm. Black ; antennae red, tarsi luteous yellow ; wings sub- 

 hyaline, stigma pale yellow. Eyes pilose, broadly contiguous, on upper half the 

 facets enlarged, the area sharply distinguished from that of the lower facets. 

 Frontal triangle very small, white pubescent, as is also the upper part of the 

 face. Antennse deep red, the extreme tip only brownish. Mesonotura shining, 

 with two remote, in the middle obsolete or wanting, white pubescent stripes, 

 appearing (iu my specimen at least) as four spots, two of which are situated on 

 the front margin, the others in front of the scutellum. Scutellum with longer 

 black pile. Abdomen flat, nearly cii-cular in outline, but little shining; third 

 and fourth segments on the anterior angles with a silvery pubescent spot ; on the 

 fifth wholly so pubescent, except in the middle. Legs black, tarsi luteous yellow. 



One specimen, Chapada. The eyes occupy nearly all the head ; 

 there is no orbital margin behind visible from the side. 



28. Rhiiigiopsis tau Boeder, Ent. Nachr. xii, 138. 



A female specimen from Rio de Janeiro (October) agrees excel- 

 lently well with the author's description of this species. The genus 

 is a good one, and quite distinct from Promerisana Walker. 



29. Rliingiopsis roititrata Wiedemann, Auss. Ins. ii, 68 (Stratiomys) ; Mac- 



quart, Dipt, i, 249 ; Dipt. Exot. i, 1, 186. pi. xxii, figs. 4.a 46 { Odontomyia). — 

 Brazil. 



A male specimen from Chapada I refer to this species, as it agrees 

 well with Wiedemann's descripticm of the female, the only differences 

 being sexual. Macquart's figure, though somewhat of a caricature, 

 will serve to show the general structure of the head. The species 

 agree closely, and, had I not recognized the species in R. rostrata 

 Wied., I should have, hesitatingly, referred my male specimen to the 

 female of R. tau. As, however, Wiedemann's female agrees quite iu 

 the abdominal markings with my male specimen (and Macquart's 

 also), I think there can be no question of the distinctness of the 

 species, the more so, as aside from the very distinct abdominal mark- 

 ings, the scutellum of R. tau is wholly black, with stouter black 



