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Show 294 INSECTA. Here the abdomen is always convex, with very distinct, and more or less triangular annuli. f which the second joint is h t f the antennre, o . . In these, t e se a 0 d r ms an angle near Its middle, d · geniculate an ,or .. much elongate ' IS . . ~ h h following one, or the last divi-at the junction of that JOint Wit t e sion of the seta. GoNIA, Meig.(l) In those, as in the other C reop h'Il re ' the seta of the antennre is not geniculate near its middle. MILTOGRAMMA, Meig. J Where the thit·d ·ol'nt of the antennre is much longer than the preceding one(2). TniXA, Meig. . 1 exceeds that of the second(S). Where its length but htt e . t ongly inflated, and, as if vesi-bd is someumes s r There the a omen I' but slightly marked; some- . h th divisions of the annu I d' cular, Wlt e d Th ings in the last case are very IS· t • es it is much flattene • e w . t~:t, and frequently somewhat arcuated exter10r1 Y · GYMNOSOMIA, Meig.-Tachina, Fab. . . d ·r vesicular or ovoid, with the Where the abdomen lS mftat~ ~·a~·~ct· the antennre are as long as separation of the annuli rather 1~ IS ~ t~ird joints of almost equal the face of the head, the secon an length, and the latter linear( 4). CisTOGASTER, Lat. Where the form of the abdomen .I S t h e same,• but the antennre are (1) Meigcn. (2) Idem. (3) Idem. (4) Idem. DIPTI<~UA. 295 much shorter, with the third joint longer than the preceding one, almost square, somewhat larger, and rounded at the end( 1 ). PHASIA, Meig.-Thereva, Fab. Where the abdomen is strongly flattened, and almost semicircular; the til>ire arc simply furnished with little hairs(2). TniOHIOPonA, Lat.-TacMna, }"ab. Where the abdomen is also flattened, but oblong, and the two posterior tibire are provided exteriorly with a fringe of lamelliform cilia(3). Sometimes the anterior face of the head presents two ranges of long hairs, forming a sort of moustachios, two of which are usually the longest, and situated at the superior extremity of the buccal cavity, one on each side. In some, the wings are vibratile, and the abdomen is narrow, elongated, almost cylindrical, or forming an elongated cone. 'fhey form three subgenera. In the wings of the two first, as in those of the preceding ones and most of the others, the two external and closed cells of the posterior extremity are almost equally prolonged backwards; the outer one extends somewhat beyond the other, and its posterior angles a.re acute. The antennre are as long as the face of the head, or hardly shorter. LoPHosu, Meig. Where the last joint of the antennre forms a very large triangular palette( 4 ). OoYPTERA, Meig. Fab. Where the same joint of those organs, hardly wider than the penultimate, resembles a linear palette, or one forming a long square. In a" Memoire pour servir a l'Histoire du genre Ocyptera,"-Ann. (1) Confounded with the preceding subgenus. (2) Lat., Genet'. Crust. et Insect., IV, 344; see also Fab. and Meigen. (3) Tbe Tltereva plumipeB, lanipeB, Fab., and various undescribed species, all from America. (4) See Meigen. |
