[2 NORTH AMERICAN DIPTERA. 



bors are scarcely more important than those of the micro- 

 tomist who cuts up frogs' eggs and makes pictures of 

 them. There are no principles too deep, no speculations 

 too lofty to find application in such creatures as flies, the 

 too often proletarians of the professional entomologist 

 even. 



Most emphatically I would impress upon all students 

 of dipterology who undertake the subject seriously, that 

 the greatest need of modern entomology is monographic 

 work. Nearly every family awaits the conscientious 

 monographer, and such work is that which lasts longest 

 and acquires most renown. The problems of distribution, 

 of relationship, of origin, of the effects of environments, 

 or the meaning and value of characters, can be satisfacto- 

 rily solved by critical monographic studies only. The 

 description of 'new species' as mere membra disjecta of 

 faunas, is scarcely worth the energies of the earnest and 

 careful student, certainly not as a life vocation, and none 

 else has any business to write at all. It too easily degen- 

 erates into a mere roll-calling, a catalogue of the permu- 

 tations of a few characters, increasing the difficulties for 

 real students who come afterward. The name that an 

 insect is known by is of trivial importance, and no one 

 cares who described it, unless he did it poorly. It will 

 be a fortunate thing when the search for 'new species' 

 and the interminably haphazard making of 'new genera' 

 is done. 



Even a cursory glance at some of the tables further on 

 will convince the intelligent student that the real mean- 

 ing of many of the classificatorv characters is yet imper- 

 fectly comprehended. But little attention has been paid 

 to homoplasy or 'convergent evolution', and as all true 

 classification must depend upon the proper use of genetic 

 characters, it is apparent that future revisions may ma- 

 terially modify our present conceptions of relationships 



