. Monographs of the Diptera of North America [microform] / prepared for the Smithsonian Institution by R. Osten Sacken. Diptera; Insects; Diptères; Insectes. 150 DIPTERA OF NORTH AMERICA. [part nota Zett. Dipt. Scand. X, p. 3781 ?) which have the ante^-^or branch of the fourth vein forked. Wlietlier we enlarge the genus, 80 as to admit these species, or whether we leave it in the accep- tation of the Fauna Austriaca, Trichosticha will contain very elcnioiits. The genus Erioptera, in Dr. Schiner's limited acceptation, is a natural group, wiiich I have retained below. It is t
. Monographs of the Diptera of North America [microform] / prepared for the Smithsonian Institution by R. Osten Sacken. Diptera; Insects; Diptères; Insectes. 150 DIPTERA OF NORTH AMERICA. [part nota Zett. Dipt. Scand. X, p. 3781 ?) which have the ante^-^or branch of the fourth vein forked. Wlietlier we enlarge the genus, 80 as to admit these species, or whether we leave it in the accep- tation of the Fauna Austriaca, Trichosticha will contain very elcnioiits. The genus Erioptera, in Dr. Schiner's limited acceptation, is a natural group, wiiich I have retained below. It is to be regretted, however, that the author transferred to this group the name of Erioptera, which belongs nmch more legitimately to his genus Trichodicha, as containing Meigeu's most numerous and typical species.* In the Froc. Acad. Nat. tici. Philad. 1859 (p. 225), I have indicated the principal groups of the North American Eriopterif. They are substantially the same as those which have been mon- fully defined in the prestnt publication. If I have retained them in the [)osition of groups'* or subgenera, it is because, in my opinion, tiie characters which all these species possess in common consti- tute between them a link of aflhiity more important than the structural differences which some of them show. Even the genus IVnjpholop/ius, as defined al)Ove, proves by the position of its subcostal cross-vein, the manner in which the second longitudinal vein originates, and, in some species, by the arcuated course uf the seventh longitudinal vein, a strong afTiiiity to the genus Erioptera in its present definition. If 1 have adopted these twd genera, it is because the difference in the pubescence of the wings of both affords a ground of subdivision as simple as easily apj))!- cable to all the species at present known. But it remains to he shown yet, whether the difference in this character is indicative of some corresponding modifications in otiier organs. Another potent reason for n
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