1913] New Application of Taxonomic Principles. 227 



thus prove satisfactory from all practical points of view. In 

 this task difficulties have been encountered which can only 

 be surmounted by conforming to lines of logical simplicity. 

 Phylogenetic facts can not be changed. The logical alternative 

 is to change our pseudophylogenetic plan of taxonomy to a 

 phylogenetic one. 



The history of muscoid taxonomy furnishes a vivid illus- 

 tration of the necessity for such change. The chronologic 

 alternation between splitting and lumping has been constant, 

 • but always gradually tending toward greater radicalism in the 

 former. Brauer and Bergenstamm were the first students 

 of the superfamily to recognize the difference in phylogenetic 

 conditions existing here and to put the idea into words. Their 

 system of taxonomy shows that they approached much nearer 

 to the truths of phylogeny than had any former students of 

 the group, but they failed in many cases to grasp the relation- 

 ships because they had no uniformly true criterion thereto 

 in the external adult anatomy. It has been left for students 

 since their time to discover criteria in the reproductive system 

 and early . stages that furnish unmistakable clues to these 

 relationships. 



It was the good fortune of the writer to figure largely in 

 the last named investigations, and therefore to obtain facts 

 which constitute a definite basis for phylogenetic deductions. 

 Once such deductions are authoritative — recognized as unmis- 

 takably founded on fact — we are able to proceed with confidence 

 in the separation of forms of diverse origin, however similar 

 may be their external morphology. This process brings us 

 face to face with phylogenetic facts that could never before 

 be confidently accepted, and with many which were never 

 before suspected to exist. It compels us to draw lines where 

 such were never before imagined, and it emphasizes with 

 extreme force the shortcomings of current taxonomy if applied 

 to young stocks. 



The writer claims in this connection nothing more than a 

 clear view and conscientious record of what has come within 

 his range of vision. The privilege of applying a phylogenetic 

 key to the taxonomy of some of the youngest and most obscurely 

 differentiated groups of insects has been his, and it has furnished 

 him an insight into the relationships of these groups and into 

 the taxonomic needs of young stocks in general that was only 



