PREFACE. iz 
Aculeates of Latreille, but possessing all but one of the yet 
discovered indigenous species of the family MJutillide of the 
Heterogyna, I have been induced to add their description ; 
consequently, to complete the first half of the aculeate 
Hymenoptera, the Formicide and the Vespide,—the first 
and the last families,—are alone wanting. These I how- 
ever purpose publishing, accompanied by an English de- 
scription of the Bees of Great Britain, containing all the 
discoveries made since the Rev. Mr. Kirby published his 
admirable ‘ Monographia Apum Angliz,’ in 1804. This 
I hope to accomplish in the course of the spring, and 
which, in conjunction with the present work, will place 
in the hands of British Collectors a description of all the 
aculeate Hymenoptera yet discovered in these islands. 
The present work, as the title indicates, contains a full 
description of all the species of the Mutillide, and of the 
fossorial Hymenoptera, known to be inhabitants of Britain, 
at least as far as they are contained in the Metropolitan 
Cabinets to which I could have access. To avoid the 
possibility of mistake, I have given very detailed descrip- 
tions, and I trust that I shall render some service to the 
science by having fully determined several previously very 
doubtful species. In the generic descriptions, I have 
omitted the cibarial organs, with the exception of the man- 
dibles, and sometimes of the labrum,—other parts, but the 
wings chiefly, furnishing, for the fossorial tribe at least, 
