206 [February, 



5 (6) Gen. $ with broad upper lamellae, blunt at upper outer angle, and bearing 



a hook at lower angle ; beneath gen. two shoi'tish black processes... 



propinquus, Egger. 



6 (5) Gen. S with upper lamellae narrowish, and armed at upper outer angle 



with a small hook, no black processes beneath ochraceus, Mg. 



7 (2) Brownish-ochreous ; gen. J with two very long sickle-shaped black pro- 



cesses bifilatus, Yer. 



8 (1) Black to blackish-brown or grey, alar expanse, 6 mm. or less. 



9 (12) Knob of halteres whitish. 



10 (11) Deep black species ; wings of male abbreviated a^er, Mg. 



11 (10) Blackish-grey species ohscurus,'Mg. 



12 (9) Knob of halteres blackish wimHww*, Mg. 



The species of the first group are very similar, and difScult to 

 distinguish, except by the male appendages ; there are, however, minute 

 distinctions which may be of assistance in determining them : I am 

 also not very certain about their nomenclature. 



M. ochraceus, Mg. : by this name I recognise a yellow^ species of 

 "which the upper lamella of the male genitalia is very long and simple, 

 rather narrow, and bearing minute black hooks at the end ; there 

 seems to be no lower lamella, but a long yellow middle piece ; the 

 frons is yellow, with a brownish dash on the middle ; the joints of the 

 antenna) are roundish ; the wings are yellow. To me it is the rarest 

 of the four species, but I have stray specimens from Penzance, Lynd- 

 hurst, and Wicken. 



M. appendiculatus, Stseg. : if I have only one species under this, 

 I am quite satisfied that it is correctly named ; the upper lamellfe of 

 the male genitalia are small, and bear at the upper inner angle a 

 longish process, and at the lower inner angle one pair of short black 

 hooks ; there is a long narrow process below shorter than in the follow- 

 ing species ; the lower lamellse seem large, and bear at the end a very 

 long, curved, thin, black hook below, between the two long black 

 sickle-shaped processes, thus there appear to be four nearly equal long 

 black processes ; it is the yellowest and smallest of all the species, 

 the frons is yellow and the abdomen scarcely at all obscure above ; 

 the wings are yellow. I have it from numerous localities in Devon, 

 Hants, Sussex, Kent, Suffolk, Cambridge, and Sutherland. 



M. propinquus, Egger : under this name I place a reddish-yellow 

 species, with the abdomen obscure above ; the upper lamellje of the 

 male genitalia are broad and blunt, almost square, at their upper inner 

 angles a little produced towards each other so as usually to touch 

 there, at their lower inner angles are short black-pointed hooks, close 



