PSYCHE. 



INTRODUCTION TO BRAUER AND VON BERGENSTAMM'S 



VORARBEITEN ZU EINER MONOGRAPHIE DER 



MUSCARIA SCHIZOMETOPA.— I. 



BY C. H. TYLER TOWXSEM). 



[The following translation of the in- 

 troductory remarks and generalizations 

 to be found in part i of Brauer and v. 

 Bergenstamm's work on Tachinidae, 

 etc., was sent me some time ago by 

 Professor J. M. Aldrich, of Brookings, 

 South Dakota. The translation was 

 made in the rough by him, and at his 

 suggestion I have revised it for publica- 

 tion. The original suggestion to pub- 

 lish it was my own. Its appearance 

 in English will, I believe, be of advan- 

 tage to American students, since a 

 growing attention is now being directed 

 to this family of Diptera in this country. 

 The introduction contains many gener- 

 alizations and valuable ideas not known 

 outside of special workers in this fam- 

 ily, and gives an insight into the meth- 

 ods of work employed by its authors, 

 which is not devoid of interest even to 

 those who may not accept in full the 

 plan of their work as carried out. 



I do not wish to be understood as 

 sanctioning the views here exposed. 

 The portion treating of head-characters, 

 other characters, relationships, etc., 

 which comprises nearly the whole and 

 is merely descriptive, is excellent. I 

 agree with the authors on what is said 

 regarding? the necessitv of smaller 



groups (at least more restricted genera) 

 in the Muscidae, but I do not sanction 

 the extreme to which thev have pur- 

 sued this plan. Finally, I can not agree 

 with what is said favoring the aban- 

 donment of generic names long in use.] 



It is a fundamental principle in the 

 development of the whole Dipterous 

 stock that, from the lowest ( Orthor- 

 rhapha nematocera) to the most dif- 

 ferentiated or highest ( Cyclorrapha 

 schizometopa), the actual value of the 

 genus, and of the systematic series gen- 

 erally, becomes less and less. This 

 proposition seems applicable to all 

 groups of animals, — in all cases the 

 most recent forms are more closelv re- 

 lated and more difficult to characterize 

 than older ones. For example, this is 

 the case in the land-snails, as compared 

 with sea-snails and mussels. The 

 cause lies in the numerous intermediate 

 forms occurring in a group of animals 

 which has just reached its period of 

 greatest prolificness. • 



But in particular cases this state- 

 ment may not be true, for there are in- 

 deed single branches of the older groups 

 which have only at the present time 

 reached the stage of multiform develop- 

 ment. With this limitation, it is true 



