pu DISTINGUISHING THE SPECIES 151 
occur. These cannot be regarded as anything 
more than geographical varieties, because inter- 
mediate examples are to be found in Orkney, al- 
though speculation as to their being species in the 
making is permissible and interesting. 
All the British species of Bomdbus are found in 
Central Europe and ten species besides, six of 
which are alpine. All the British species of 
Psithyrus also occur there and one besides. 
The last revision of the British Boméz and 
Psithyrt was made by Saunders in his Hymenoptera 
Aculeata of the British Lslands, published in 1896. 
The only alterations in the British list of species | 
am here making is the reinstatement as species of 
the three forms, 2B. lucorum, B. ruderatus, and 
LB. distinguendus, previously recognised as distinct 
by Smith, the addition of Pszthyrus dtstinctus, and 
the changing of the names &. venustus and 
B. smithianus to helferanus and muscorum re- 
spectively, as the result of the clearing up of the 
confusion between these two species. 
For each of the species of Aomdbus suitable 
English names have been chosen in the hope that 
they will be of assistance to young students. 
