ENEMIES OF APHIDES. 



131 



several very beautiful and exact coloured plates of various species, 

 with many descriptions. His plates usually represent the rare 

 rather than the ordinary varieties, and thus their value to the 

 student is for special rather than everyday studies. They are, 

 however, almost unequalled for accuracy of drawing and delicacy 

 of colouring. Many of the generic and specific descriptions have 

 been since abandoned. 



Some fifteen years later Walker described the family among his 

 Diptera, but added little to our information concerning it. Schiner 

 and Meignen have written with authority on the Diptera of Europe, 

 and the works of both, published in German, are standard. In 

 1864 the former proposed some extensive changes in the arrange- 

 ment of this order, and a few years later Osten-Sacken produced 

 his classification. 



At present Mr. Verrall's lists of Diptera are our best authority 

 as regards the family of Syrphidce, and I take the following list of 

 genera and species from his issue of 1888, adding to the latter, 

 by the kindness of Mr. C. J. Watkins, a few species which have 

 been noted since. These are italicised, while the known aphidi- 

 vorous specimens are starred. 



Genera comprised in the Family Syrphid^, 



from Mr. G. H. Verrall's list of British Diptera, published in 1888 : 



Number of Number of 



Genus. ^ Species. Genus. Species. 



1 Paragus (Lat.) ... 2 12 Didea (Macq.) ... i 



I species added since i888 



2 Pipizella (Rud.) 



3 Pipiza (Fin.) 



4 Cnemodon (Egg.) 



5 Orthoneura JMacq.) .. 



6 Chrysogaster (Mg.) 



7 Chilosia (Mg.) 



I species added since 1888. 



8 Leucozona (Schin.) 



9 Melanostoma (Schin.) .. 



10 Pyrophoena (Schin.) .. 



11 Platychirus (St. Farg.) ., 



I species added since 1888. 



