Hitherto but a single genus(Conops) of this group has received general accepteance among dipterologists. A second genus, Physocephala, was based by Schiner on characters in themselves of but little importance, and which I did not deem sufficient to separate our species in the first paper I published* on the North American forms. A further study, however, convinced me that they were sufficiently constant to warrant their use, particularly in connection with other important ones in the neuration, which I pointed out.