ORTALID^E. INTRODUCTION. 31 



ovipositor, similar to that of the Ortalidse, sufficiently distinguish 

 the Sapromyzidx and Sciomyzidse. 



DIAGNOSTIC OR ARTIFICIAL DEFINITION OF THE ORTALID^B. 



The statements about the relationship of the Ortalidse prove 

 that the following characters are sufficient to distinguish this 

 family from all the others, in other words, to constitute its arti- 

 ficial definition. 



Male with a rolled-up, long penis ; female with a three-jointed, 

 horny ovipositor, ending in a simple point. Front without a 

 second lateral row of bristles. No vibrissse. Complete venation 

 of the Diptera acalyptera ; auxiliary vein distinct to its very tip, 

 ending in the costa at an acute angle; the two posterior basal 

 cells large. The middle tibiae alone are provided with spurs ; all 

 the tibiae are without an erect bristle before the end of their 

 upper side. 



