Among the insects obtained by Prof. F. H. Snow in a recent trip to Colorado, is an excellent representative collection of the Diptera. The material for the following notes on Syrphidae is chiefly drawn from this collection. That such a collection affords so many points of interest in this, one of the best studied families of North American Diptera, is an evidence of the rich field that is presented by this important and little-studied order of insects. CALLICERA. _Callicera_ Panzer, Fauna Germanica, 1806. _Callicera_ is a small genus hitherto supposed to be peculiar to Europe. The species are found in the high mountains, where the males are often taken while hovering in the air. The present collection includes numerous specimens of a species taken near the summit of Mt. Deception, in Manitou Park, Colorado, at an altitude of nine thousand feet. The occurrence of members of this genus in the western part of the United States is a fact of especial interest and further substantiates the rule that American forms common to Europe are more apt to occur in the western regions. _Arctophila flagrans_ Osten Sacken, is a case precisely similar to the present one, belonging as it does to a small European genus of mountain flies, and described from Colorado. As the genus is a new one to our fauna, I here give an amended transcription of the generic characters from Schiner’s Fauna Austriaca, to include the new species, which differs only in unimportant details. =Callicera.= Rather large, stout, green or black species with metallic lustre and abundant, long pile. Head hemispherical, somewhat broader than the thorax. Antennae porrect, longer than the head, somewhat remote at their base, inserted upon a protuberance of the front; first joint sometimes elongate; second joint shorter than, or as long as, the first joint; third joint one to three times the length of the first two joints taken together, with a short, terminal style. Face broad, under the antennae concave in profile; an obtuse tubercle below the middle; on the sides thickly covered with pile. Proboscis rather prominent, with broad labella. Eyes hairy, holoptic in the male. Abdomen elliptical, as long or longer than the thorax. Legs moderately strong. Third longitudinal vein straight, first posterior cell distally short petiolate; marginal cell open; cross-vein situated near the middle of the discal cell, oblique. =Callicera montensis, n. sp.=, Plate vii, f. 4.