viii 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 Bombus 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 Bombi and 

 Psithyri was made by Saunders in his Hymenoptera 

 Aculeata of the British Islands, published in 1896. 

 The only alterations in the British list of species I 

 am here making is the reinstatement as species of 

 the three forms, B. lucorum, B. ruder atus, and 

 B. distinguendus, previously recognised as distinct 

 by Smith, the addition of Psithyrus distinctus, and 

 the changing of the names B. venustus and 

 B. smithianus to heifer amis and muscorum re- 

 spectively, as the result of the clearing up of the 

 confusion between these two species. 



For each of the species of Bombus suitable 

 English names have been chosen in the hope that 

 they will be of assistance to young students. 



