1830. Proctotrypides, Family (partim), Leach. Edinb. Ency., IX., p. 145.

1830. Mutillidæ Family (partim), Leach. Opus cit., p. 147.

1839. Cenoptera, Tribe 6, Haliday. Opus cit.

1877. Cenoptera, Tribe 12, Forster. Ueber d. Syst. Werth d. Flugelg., p. 20.

The family was first defined by that astute British systematist, A.H. Haliday, who, as early as 1839, very correctly placed the family among the Fossores.

In 1893 the writer, in his Monograph of the North American Proctotrypidæ, followed the views of Prof. Westwood, and treated these insects as a subfamily in the Proctotrypidæ. Since that time, however, the extensive studies I have made into all families of the Hymenoptera have given me a much broader and more thorough knowledge of the families and their affinities, and I am now convinced that Haliday was right, that these insects are allied to the fossorial wasps, and have nothing to do with genuine Proctotrypoids; they are clearly alied to the Chrysididæ, through the Cleptinæ and Ameriginæ, and to the Sapygidæ, Tihiidæ, Cosilidæ, Thynnidæ, Myrmosidæ and Mutillidæ, –all parasitic families.