Orthorrhapha Bracht/cera. 373 



questions of tlie definition of zoological groups, there is no rule witli- 

 out cxceptions. In the groups of a higher Order espccially ex- 

 ceptioiis are more frequent and niore startling. But these exccptions 

 themselves are subject to rules: if we have Diptera without wings, 

 and even without halteres, we have none, and cannot have any, with 

 four wings. 



Ever since 1892, I have bccu engaged in the task of fürt her 

 developing the new arrangement which I introduced in that yoar. I 

 have collected many facts and observations, of which niy prescnt 

 conimunication is a niere outline. Still, it contains enough, I hope, 

 to make my fundamental idea clear, and to enable othcrs to follow 

 it up, if they happen to agree with it. The Standing diflieulty I 

 have encountered in all luy entomological work, is vvant of scientific 

 training, too late to mend at the rather advanced age whcn I began 

 indcpendent research. I offen feit that the last word in certain 

 (jucstions was not for nie, because it depended on anatoniy. Of this 

 liniitation of my compotence, I will give tvvo instances. Having 

 suggcstcd the iniportancc of the structurc of the head, in matters of 

 Classification, I attcmpted a comparative study of heads and eyes in 

 dift'erent families and in dift'ercnt genera of the same family, and 

 accumulated enough material to furnish a theme for a publication 

 (in fact, I promised such a publication in my paper of 1892, Berl. 

 Ent. Z. p. 449, footnote). But I gave up my purpose, when I found 

 that my results would remain unsatisfactory, unless accompanied by 

 dissections, like those of Becher in his short, but very instructive 

 paper, already quoted by me (Wien. Ent. Z. 1882). In the same paper 

 of 1892, I tried to prove that each Superfamily niay be expected to 

 possess a characteristic type of structure for the antennae, and I 

 even attenipted to formulate a definition of such a type for the i^'enio- 

 cera vera and the Eremochaeta. A priori, I am convinccd that 

 the existence of such an antennal formula (more or less dofinablc) 

 for each Superfamily must underlie the importance of the antennae 

 as Organs of orientation, and I even foel that, in a certain mcasure, 

 I could attempt such a definition for the antennae of the threc Supcr- 

 familics which I introduce in the present paper. But I loavo it for 

 othcrs to do, conscious as I am that such an attempt caunut prove 

 satisfactory without the help of dissection, 



My paper is, therefore, a hallen d'cssai which I launch, attcn- 

 tive to the course it will follow! 



