1802.1 151 



which is usually divided in the middle by a fine, black, longitudinal line ; the frontal 

 space behind is wide, and of a dull black colour, having an indistinct broad central 

 stripe ; the fronto-orbital bristles are in a double row behind, and are interrupted 

 by the silvery plate emerging in a single row in front of it ; face glistening white, 

 with black reflections ; cheeks with a few soft hairs on their upper part ; facialia 

 ciliated with strong bristles nearly to the top ; palpi black ; antennaj black or grey ; 

 arista thickened to a little beyond the middle ; thorax dark grey, with four black 

 stripes and three post-sutural outer dorso-central bristles ; abdomen with white or 

 yellowish reflections, and marked on each of the last three segments with three sub- 

 triangular black spots ; wings with several (5 to 8) small setce along the base of the 

 third vein, apical cross vein much curved ; legs black. 



? . Forehead less prominent than in the male, and without the glistening 

 plate ; frontal stripe black, extending to the base of the antennae, and wider than 

 the sides of the froiitalia, which are silvered on their front pai'ts with white glitter ; 

 it is similar in other points to the male. Not rare. 



M. AEGTROCEPHALA, MgU. 



Both sexes of this species bear a very strong resemblance to the female of M. 

 leucocephala, and have often been confounded with it ; they differ, however, by [1521 

 being usually rather smaller, by having tlie frontal stripe (which extends to the base June, 1892. 

 of the antennse in both sexes) narrower, it not being wider than the sides of the 

 frontalia ; by the facial setse being less ; by the thorax being of a lighter grey and 

 more distinctly striped ; by the abdomen also being more cinereous, and marked by 

 more clearly defined triangular spots ; lastly, the arista is not thickened quite so 

 far. The males and females are very much alike, but can be distinguished by the 

 difference in the fronto-orbital bristles, those of the male being only in a double row 

 at the back part. Rare. It is in Mr. Dale's collection, and I captured a single 

 specimen in Kent in 1888. 



M. CAMPESTRIS, rin. 



Frontal stripe much wider than the sides of frontalia ; forehead slightly promi- 

 nent ; sides with face silvery-white, with dark reflections ; cheeks without any hairs ; 

 arista with only basal third thickened (Meigen and Schiner say half) ; thorax with 

 four moderately wide dorsal stripes, and three post-sutural outer dorso-central 

 bristles ; abdomen with silvery-white reflections, a central row of subtriangular spots 

 and transverse sinuous bands, forming semilunar or irregular triangular spots on the 

 sides of the segments ; the male is usually more distinctly marked than the female, 

 and has the fronto-orbital bristles only double at the hinder part ; in other points 

 this species resembles the former ones. Not common. 



M. AMABILIS, Mgn. 



This closely resembles M. campestris ; the chief points of difference are that 

 the forehead is a little more prominent, the arista is only tliickened for a short 

 distance at the base, and the longitudinal and ti-ansverse bands on the abdomen are 

 nearly straight instead of being maculiform. Very rare. 



