Prof. Westwood and others confused these wasps with the Vespidæ and the Eumenidæ, although Latreille had years previously established his family Masarides. Henry de Saussure, in his “Etudes,” treats them as a tribe. They, however, represent a distinct family close to the Eumenidæ but easily separted from them and the Vespidæ by the wings not being folded longitudinally, by peculiarities of the antennæ, which are usually strongly clavate at tip; by the wholly different abdomen, the venter being flatter; and by the much larger scutellum.

Of the habits of the Masarides nothng seems to be positively known. Some years ago Dr. Dyar gave me specimens of Masaris vespides, Cr., bred from what I take to be the nest of an Odynerine, taken in Arizona.