, NOTES ON DIPTERA. 181 



I 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 Dropetis being 



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



i 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, Devonshii'e, and Cornwall. 



i Argyra, Macquart. Founded upon Porphyrops diaphanus, 

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

 division of that genus. 



Medetenis 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. 



Madtccriiim 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 sti'aight. 



P. atra, Meigen, and P. holosericea, Meigen. August, on 

 grass beneath trees near London. 



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

 pedes picei, metatarsi vix incrassati, alee fulvofumosce, nerviis 

 5i^^. longitudinalis rnarginem attingens, nervus transversus 

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

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



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

 pedes atri, metatarsi valde incrassati, alee JumosdB, nervus 

 5"^ longitudinalis abhreviatns, nervus transversus ordinarius 

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

 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. 



