60 [March, 



iusufficient knowldege or mere carelessness, incorrect in their applica- 

 tion of them ; not a few of these mistakes have been handed down for 

 generations until some person has been enterprising enough to consult 

 the original author's work. 



In Biptera there ai-e a number of such instances. Thus De Greer's 

 Tiftda culiciformis was for long assumed to be a species of Corethra, 

 but is now known to be the same as MocMnnyx velnfinns. The purpose 

 of the present note is to call attention to three more cases which have 

 apparently been overlooked. Unfortunately, these affect the names of 

 four of our commonest British Diptero, but as the changes will have 

 to be made some day, they had better take place now. It is, moreover, 

 some compensation for the inconvenience caused, to reflect that for 

 once the Law of Priority has brought belated justice to a really sound 

 naturalist. 



1.— TiPULA FUNUORUM De Geer. (Mem., Tome VI, p. 361). 



DeGeer found some Dipterous larvae, in a fungus (Boletus luteus), 

 which he described and figured, but failed to rear. In the following 

 year he found larvae again in the same species of fungus, and hatched 

 flies from them. Naturally he assumed that he had dealt with only 

 one species, to which he gave the name Tipnla fungorum. Later on 

 Meigen had an insect which he thought to be the same as De Greer's, 

 but for which he proposed the name Mycetophila fusca. Fifty years 

 later Winnertz included what he considered to be the same species in 

 the genus Exechia, restoring to it De Geer's name of fungorum, and 

 recently E. fuvgorum has been selected by Johannsen as the type of 

 the genus Exechia. 



Now in the light of our present knowledge, it is clear that (a) the 



larva figured by De Geer is that of a BoUtopliila, as shown unmistake- 



ably by the large antennae ; {h) the fly described by De Geer is our 



Mycetophila punctata, as shown both by the general description, and 



the figure (quite recognisable) of the male genitalia; (c) Meigen's 



M. ftisca was a totally different insect, he being appai-ently misled by 



an inaccuracy in De Geer's figure of the wing : M. fusca is doubtless 



an Exechia, perhaps, as Meigen describes the thorax as having three 



black stripes, the same as the species we know as E. trivittata, though 



only an examination of the type can settle this ; (d) Winnertz' s 



Exechia fungorum was a different insect again, clearly not the same as 



*■ 

 Meigen's M. fusca, since the thorax is unstriped, and certainly not at 



all related to De Geer's T. fungorum. 



