INTRODUCTION. 



This Volume includes the enumeration of the Families Syrphidae, Conopidae, Pipuncu- 

 lidse, and Platypezidse, contributed by Prof. S. W. Williston, the date of publication 

 of his work extending from December 1891 to May 1892, the closing-up of the subject 

 having been deferred till Vol. II. was completed. As with the preceding Volumes, a 

 list of the species described from Mexico or Central America by other authors during 

 the progress of the work is appended, this list including only such as have been 

 recorded since 1891. These have been mainly contributed by Dr. Giglio-Tos; and 

 as the date of publication of his paper is later by one month than that of the 

 final instalment of Prof. Willistons, the last-mentioned has priority in every case 

 where the same species has been described by both authors. The two coloured 

 Plates of Syrphidse and Conopidse have been prepared by Mr. Wilson, of Cambridge, 

 from drawings made by Van der Wulp. 



Ed. 



August 1903. 



