NOTES ON DIPTF.RA. 181 



they are not easily recognized among the endless numbers of 

 Borborites, which they resemble in form and habit. Like 

 them also they are infested by Acari, often so much so as to 

 appear like moving heaps of those animals, the Drapetis being 

 concealed from the sight, and scarcely able to run. I have 

 seen them also in North Wales. D. Jlavipes inhabits the 

 same localities near London, and in the New Forest, Hamp- 

 shire, but is much rarer. D.fuscipes lives on the coasts of 

 Wales, Devonshire, and Cornwall. 



Argyra, Macquart. Founded upon Porphyrops diapkanus, 

 argyrius, and the other species belonging to Meigen's first 

 division of that genus. 



Medeterus conspersus, Haliday. September, in swampy 

 spots on mountains in Westmoreland, Cumberland, and North 

 Wales, particularly abundant on the summit of Plynlimmon. 



M. alpinus, Haliday. With the preceding, but much rarer. 



Mac/i cerium maritimum, Haliday. June, on the sea-coast, 

 near Lymington, Hampshire. 



Platypeza picta, Meigen. The largest and handsomest 

 British species of Platypeza, and has most development of 

 the character whence the generic name is derived. Found 

 near London in the spring. 



P. dorsalis, Meigen. August, on grass beneath the trees, 

 near London. The little nervure, which unites the two last 

 longitudinal nervures, at the lower base of the wing of this 

 species is curved and short, in the others it is long and straight. 



P. air a, Meigen, and P. kolosericea, Meigen. August, on 

 grass beneath trees near London. 



P. fumipennis. Mas. Aterrima, kolosericea, halteres et 

 pedes picei, metatarsi vix incrassati, alee fulvofumosce, nervus 

 5 US . longiiudinalis marginem attingens, nervus transversus 

 ordinarius margini proximus. (Corp. long. lin. 2 ; alar. fin. 

 4.) August, on grass beneath trees near London. 



P. aterrima. Mas. Aterrima, kolosericea, halteres et 

 pedes atri, metatarsi valde incrassati, alee fumosce, nervus 

 5 US . longiiudinalis abbreviatus, nervus transversus ordinarius 

 margini proximus. (Corp. long. lin. If ; alar. lin. 3|.) 

 July ; on grass beneath trees near London. 



Callomyia elegans, Fabricius, C. speciosa, Meigen, C. 

 antennata, Fallen. Found in summer on grass beneath trees 

 near London. 



