. Monographs of the Diptera of North America [microform] / prepared for the Smithsonian Institution by R. Osten Sacken. Diptera; Insects; Diptères; Insectes. AMALOPIS. 2C3 0. S., and in the European species A. Ultoralis M., i^chineri Egg., (jiriilla yi. The stnioture of tlio posterior fork of tlie fourth vein undergoes sonic niudiiicatious which deserve likewise to he nii'iitioned. In must of tlie species (aiiri]i(nini}<, JnjjH'rborcn, fol- iar, ineondcniti, and tlie Euroiiean liUoralis ^I., lipnlina Eggcr, schincri Kolen., unicolor Sehuni., itnmaculata Sehuin.)this fork is petiolate, or in
. Monographs of the Diptera of North America [microform] / prepared for the Smithsonian Institution by R. Osten Sacken. Diptera; Insects; Diptères; Insectes. AMALOPIS. 2C3 0. S., and in the European species A. Ultoralis M., i^chineri Egg., (jiriilla yi. The stnioture of tlio posterior fork of tlie fourth vein undergoes sonic niudiiicatious which deserve likewise to he nii'iitioned. In must of tlie species (aiiri]i(nini}<, JnjjH'rborcn, fol- iar, ineondcniti, and tlie Euroiiean liUoralis ^I., lipnlina Eggcr, schincri Kolen., unicolor Sehuni., itnmaculata Sehuin.)this fork is petiolate, or in other words, the inner end of the fourth posterior cell (enclosed by this fork) is more remote from the basis of the wing than the inner end of the diseal cell, or when it is open, of the third jiosterior cell. In ^1. vernaliH, however, as well as in the European A. occuUa ^L, (jinundcnsia Egger, and ojuu-a Kgger, the posterior fork of the fourth vein is sessile, that is, the origin of the branch forming it is coincident with the first branch- ing of the fourth vein ; hence, the inner end of the fourth posterior cell is ecpiidistaiit from the basis of the wing with thu inner end of the diseal cell, or, when it is open, of the third jiosterior cell. The diseal cell is closed in the normal specimens of A. cah-nr, vcrnalis, and inconslans ; it is likewise closed in the two reinain- iiig North American species, A. auripennlx and A. hyperhorea, of which, however, I have onh' single specinunis before me; also in the European A. tipuUna Egger. In the European A. liltor- fl//.s M., iichincri Kol., and iinivolor Schum., the diseal cell seems to be variable, sometimes closed, often open. In A. occulta, M., imiitaridata Sch., gmundensis and opaca Egger, it is open (at least iM normal specimens).* The shape of the diseal cell is usu- ally pentagonal; but in A. vernalix, owing to the above-mentioned structure of the posterior fork of the fourth vein, it is elongated and narrow. When the d
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