INCOMPLETE as our knowledge of the North American Trype- 

 tina is, our scanty materials are, nevertheless, sufficient to enable 

 us to form an approximate idea of their relation to the European 

 fauna. Even a superficial comparison of a North American with 

 a European collection of Trypetse will show, that certain sub- 

 genera, characteristic for Europe by the number of species which 

 represent them, are absolutely or almost wanting in America, 

 while, on the contrary, North America possesses other, very 

 peculiar forms, which do not occur in Europe. 



We will notice, in the first place, that the subgenus Urophora, 

 which, in Europe, embraces fully one-eighth of all the species, is 

 not represented at all in North America. 1 Next to this, we 

 become aware of the fact that the subgenus Trypeta, containing 

 another eighth of all the European species, is represented in 

 North America by Trypeta palposa only, besides Trypeta flores- 

 centise Lin., which is very probably imported from Europe. 



As forms peculiar to North America and entirely foreign to 

 the circles of relationship of the European Trypetina, the species 

 of the subgenera Hexachseta, Acrotoxa, Blepharoneura, Acro- 

 tsenia, Eutreta, and Acidogona deserve especial attention. 



Besides these two very striking differences between the two 

 faunas, a close comparison reveals other discrepancies ; as, for 

 instance, that less characteristic European subgenera are entirely 

 wanting in North America, while subgenera occurring in North 



1 In South America likewise, no species of Urophora have as yet been 

 found; all the South American species published by European authors as 

 Urophorce do not belong to this genus at all ; most of them are not even 

 Trypetidce, but Ortalidce, with black crossbands on the wings. 



(331) 



