. Monographs of the Diptera of North America [microform]. Diptera; Insects; Diptères; Insectes. lY. ON THE NORTH AMERICAN EPHYDRINIDAE. The family of Ephydnnida: is taken licrc altogether in the extent which was ^\\Gn to it by Stenhamniar, the diligent monographer of the Swedish species, and by Walker in his work on the British Diptom, ijie latter founded on Haliday's valuable observations. The characters easily distinguishing the Ephydrimdoß from all the other families of Diplera acuh/ptera may be set down as fol- lows: Face more or less, often considerably convex; either with- out any impres
. Monographs of the Diptera of North America [microform]. Diptera; Insects; Diptères; Insectes. lY. ON THE NORTH AMERICAN EPHYDRINIDAE. The family of Ephydnnida: is taken licrc altogether in the extent which was ^\\Gn to it by Stenhamniar, the diligent monographer of the Swedish species, and by Walker in his work on the British Diptom, ijie latter founded on Haliday's valuable observations. The characters easily distinguishing the Ephydrimdoß from all the other families of Diplera acuh/ptera may be set down as fol- lows: Face more or less, often considerably convex; either with- out any impression at all beneath the antennae, or moderately im- pressed, but never provided with membranous antennal furrows. AntennjG short, first joint small; antennal bristle either nearly bare, or pubescent, or pectinated on the ui)per side only. Oral cavity rounded, in most of the genera of considerable size; cly- peus distinct, in some genera retracted in the oral cavity, in the remaining genera prominent over the oral margin, in some of them of a rather large size; palpi small; mentum short, more or less in- Thorax rather quadrangular; scutellum proportionately large. Abdomen of very variable form, consisting of six seg- ments in the males; the fer'oles have one short, and generally not distinctly visible, segment more. The sixth segment being al- ways small and generally much concealed under the fifth, the struc- tural relations depend on the conformation of the five first seg- ments; of these tlie first is often much shortened and sometimes nearly connate with the second, a circumstance which has led authors to omit it in the enumeration or to count the two first segments for one; this is to be borne in mind in order to understand their descriptions; in mine, I have always counted the first seg- ment as distinct, however difficult it may be to observe it. The fifth segment is also of very variable structure, gciierally nearly equalling the foregoing in size, rarely co
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