NOTES ON AUSTRALIAN DIPTERA. No. vii. By J. R. Malloch. (Communicated by Dr. E. W. Ferguson.) (Twenty-three Text-figures.) [Read 30th September, 1925.] In this paper I present notes on some previously described species and descriptions of some others that appear to be new to science. With the exception of one species which belongs to the British Museum, all the types will be sent to Dr. E. W. Ferguson, from whom most of them were received for identification. Family Sepsidae. The members of this family have a characteristic ant-like appearance that readily distinguishes them from most of their allies. Hendel's most recent papers dealing with the acalyptrate Diptera give prominence to the presence or absence, divergence or convergence, of the postvertical pair of bristles as characters for the separation of the families. While one must admit that these bristles are quite important as criteria in grouping the insects, a careful scrutiny of the families discloses the fact that, just as is the case with other characters, there are some departures from the general rule here. Hendel ascribes to Sepsidae divergent postvertical bristles, but in one of his papers he parenthetically refers Eurychoromyia Hendel to the family, despite the fact that it lacks these bristles. I rather incline to doubt the propriety of assigning this genus here, but have not seen it, so cannot give a definite opinion on the point. However, there is one undoubted sepsid amongst the Australian material before me, which lacks the postverticals, and for which I herein propose a new genus. The preapical tibial bristle is stated to be absent by Hendel, but I am confident that in some species it is present, though small and weak, as I can detect a setula or short bristle in practically the normal position in these. Strictly speaking the family is distinguished from its nearest allies by the distinct auxiliary vein, which is complete and well separated from the first vein; the presence of vibrissae; bare, or almost bare, arista; absence of presutural dorsocentral bristles; presence of one or more long setulose hairs on lower margin of metathoracic spiracle; incomplete sixth wing vein; lack of pteropleural and sternopleural bristles; and the vestigial palpi. The postvertical bristles are absent or present; when present they are divergent; orbit with, at most, one distinct bristle. In 1906 de Meijere published a revision of the Indo-Australian species of Sepsis in which he recorded two species from Australia (Ann. Mus. Nat. Hungar., vol. 4, p. 165). I have both of these species before me, as well as one he described from Singapore, but did not record from Australia, and in addition have three related forms as yet undescribed, for two of the latter having to propose new genera in this paper.