346 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser 



genus makes their study very difficult. It has usually 

 been the practice to break up a genus which has become 

 unwieldy, provided definite and stable characters are 

 available for the separation of the sexes into their respec- 

 tive genera. With the Genus Pipiza it is found that 

 there is a natural subdivision into four well-marked 

 groups. In Europe three genera are recognized, Pipiza, 

 Pipizella and Cnemodon. The genus Heringia, estab- 

 lished by Rondani for Pipiza heringi Zett., is also 

 recognized in the present paper, and includes five North 

 American species. 



As to the wisdom of accepting four distinct genera I 

 might point out that the material for study has in- 

 variably been scanty, that too much emphasis has been 

 placed upon certain prominent characters (for example, 

 hind trochanteral spur in Cnemodon) to the detriment 

 of the further study of other characters; that the fe- 

 males, except in some species of Pipiza, have never been 

 properly associated with the males, and that, on account 

 of the confusion caused by the difficulty of proper iden- 

 tification, the genus has never received careful study. 



With such a condition prevailing in these genera it 

 is no wonder that the generic limitations prevailing in 

 Europe have not been accepted in America. The diffi- 

 culty of tracing the females to their proper relationships 

 has now been largely overcome, so it is a simple matter 

 to locate them in their proper genus. 



I wish to express to Professor A. L. Lovett, of the 

 Oregon Agricultural College, the greatest thanks for 

 specimens loaned for study and for many suggestions. 

 Upon learning of the scope of the present work, Pro- 

 fessor Lovett unhesitatingly forwarded his whole col- 

 lection of Pipizini for study, requesting that all new 

 species be named and described, including such as he 

 already had in manuscript. Mr. W. M. Davidson, of 

 the Bureau of Entomology, supplied several specimens 

 of California Pipizini which he considered new and of- 

 fered a number of suggestions for which I am greatly 

 indebted. I also wish to express my gratitude to Dr. 



