32 PSYCHE [April NOTES ON THE SYNONYMY OF THE SPECIES OF ERAX OF THE EASTERN UNITED STATES. BY CHARLES W. JOHNSON, BOSTON, MASS. In most catalogues of insects tliere are some names in use which we know should be changed. This fact is brought forcibly to our minds in preparing faunal lists, and that such names should no longer be used is evident; a faunal list, however, is no place for such changes, which often require some elucidation. That the present names in use for the common species of the genus Erax are misa])})lied, is evident to all systematic dipterologists. Working on three faunal lists has compelled me to take up this matter, for it does not seem desirable to continue to perpetuate these discrepancies. While the following synonymy has been largely intimated by Baron Osten Sacken, and Dr. Williston, authors have failed to realize its significance. Erax aestuans (Linne). Asilus aestuans Linne, Syst. Nat., 12 ed. 1007, 1767. Dasi/pogon aestuans Fabr., Syst. Antl. p. 164, 1805. Asilus macroJahis Wied., Auss. Zw. Ins., I, 458, 1828. Asilus aestuans Macq., Hist. Nat. Dipt., I, 312, 1834. Erax femoratus Macq., Dipt. Exot., I pt. 2, p. 115, 1839 (cJ^). Erax incisuralis Macq., Dipt. Exot., I, pt. 2, p. 117, 1839 ($ ). Erax bastardi Macq., Dipt. Exot., I, pt. 2, ]). 117, pi. 9, f. 7, 1839 (6" 9 ). Erax tibialis Macq., Dipt. Exot., I, pt. 2, p. 118, 1839 9 . This is the most common and variable of the eastern species of Erax. It is on the other hand the only one with three white abdominal segments, therefore, it seems that the brief description of Linne can only a]iply to this species: "cinereus abdominis ulfimis tribus segmentis albis. Habitat Pennsylvania." The number of white segments, however, varies from three to four, the latter representing the A. inacrolabis of Wiedemann. If this was constant its specific standing might not be questioned, but among the sjiecimens before me are many intermediates in which the dorsal portion of tlic foin-th segment is blackish leaving very broad posterior and lateral margins of white. As to INIacquart's species there seems to be no question as to the synonymy.