ter ris a sharo definition of each of his families, 

 conceived as thf^y are purely throug:h natural in- 

 tuition. The more a^nazing is it that all the 

 sai]p he has been able , one may be tenipted to 

 say, by divine inspiration, to aporehend correcfly 

 the essential' idea of most families and even with 

 rare skill succé ssfully ärrande their species 

 into ^la.jor groups. "»»e ought to continue along 

 the road first oaved by him. Then as a first step 

 v^e should undertake a close investigation of the 

 structural differences Vv'hich particularly 

 oharacterize the family and give a clear definition 

 of the same . 



For t his purpose it v/ill be necessary to 

 initiate a general investigation and revision of 

 all the Sfoecies. Forsm will be disc'' osed which 

 Tierely on account of analogous de velop^nents and 

 similar habitus have been placed in a family to 

 which they do not belong and from which they con- 

 sequently must be remo^^^Bd, and forms, intermediate 

 betv.'een large families, vrill be discovered which 

 in the original more compr^hensive arrangements 

 have been placed close to central groups with 

 which they only exhibit a ra the r re möte relation- 

 ship and from v/hich they .nay be separated as 

 families of lower rank. 



Sone suGcessful attempts have been accomplished 

 to impro^^ the sys te mat ic arrangeriBnt of the 

 Diptera by a separation of the interraediate major 

 groups. lifeny examples of this kind can be found 

 in Professor J. \h, Zetterstedt' s works. But the 

 species have seldom been arranged according to the 

 sa^Te rules as the families, and shall the system 

 which science for-nulates come near to nature's 

 own system, then it must be considered imperative 

 to ar ra nge not only the major groups (the genera) 

 according to the de\relopnient of the more imoortant 

 organs but al so the groups of minor rank (the 

 sections). 



It is adnitted that sections estabiished on 

 characters as the shape or color of certain of ten 



