Czl £2-S~ 



PROCEEDINGS 



CALIFORNIA ACADEMY OF SCIEN&ES? 



Fourth Series 



Vol. XI, No. 16, pp. 345-393, 30 text figures December 31, 1921 



XVI 



REVISION OF THE PIPIZA GROUP OF THE FAMILY 



SYRPHLDiE (FLOWER-FLIES) FROM 



NORTH OF MEXICO 



BY 

 C HOWARD CURRAN 



Orillia, Ontario, Canada 



The genus Pipiza, as generally accepted in North 

 America, has long been regarded as one of the most 

 difficult genera in the family. The reason for this is 

 found in inadequate descriptions and the absence of 

 outstanding specific characters which could be used for 

 identification. Abundant material has revealed several 

 characters which are of exceptional importance in this 

 group and the old reliance upon the color of the pile is 

 not adhered to in this work where other characters are 

 sufficiently prominent to allow of their employment. 

 The character of the pile often indicates species and is 

 of considerable importance, as variation is not as great 

 as is generally supposed. Many small differences usual- 

 ly accompany its variation in color, and these, together 

 with more important structural differences, lead to the 

 absolute determination of the specimens. 



The present paper deals with forty-nine species of 

 North American Pipizini. Their retention in a single 



December 31, 1921 



