. Bulletin - United States National Museum. Science. 476 UNITED STATES NATIONAL MUSEtTM BtJLLETIN 2 24 Nerax, new genus FiQTJBES 388, 740, 1381, 1390 Erax of American authors generally; not Erax Scopoli, 1763. Type of genus: Asilus aestuans Lirme, 176", by present designation. The species of Nerax are medium size to generally large flies, composed of numerous species and species gi-oups confined to the New World. They are readily characterized by the prominent, bristle-covered gib- bosity of the face, tlie numerous, stout bristles, the tapered abdomen m which the male terminalia forms a c
. Bulletin - United States National Museum. Science. 476 UNITED STATES NATIONAL MUSEtTM BtJLLETIN 2 24 Nerax, new genus FiQTJBES 388, 740, 1381, 1390 Erax of American authors generally; not Erax Scopoli, 1763. Type of genus: Asilus aestuans Lirme, 176", by present designation. The species of Nerax are medium size to generally large flies, composed of numerous species and species gi-oups confined to the New World. They are readily characterized by the prominent, bristle-covered gib- bosity of the face, tlie numerous, stout bristles, the tapered abdomen m which the male terminalia forms a characteristic, enlarged, elongate, laterally com- pressed and clublike structure. The fully inflated scutellum sliould be noted. The posterior branch of the third vein ends before, at or slightly beyond the apex of the wing and near the base of tlie anterior branch of the third vein there is often a spur vein with the base itself formed like a crossvein, or this spur may be quite absent and the base arising gradually. Length 12 to 35 mm. The decision as to a proper and satisfactoi-y name for the very large, New World group of flies, which have previously gone under the name of Erax Scopoli, through an error of interpretation by Macquart, is much involved. Hine, 1919, noted this situation with- out rectifying it and without comment on the prior claim of European species to the name Erax. Hine designated an American species as type of genus for Erax Scopoli, overlooking the fact that Coquillett, 1910, had previously designated one of Scopoli's included species as the type of genus of Erax Scopoli. I am indebted to Mr. H. Oldroyd for calling to my attention the confusion which has long existed with respect to the European robber flies which have been currently placed under the name ProtopJmnes Loew. For type of genus I choose Asilus aestuans Linne be- cause it is a typical and ubiquitous species within the genus, of wide range and can not be confused with 'Efferia Coquillett or ot
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