236 [September, 



P. MELANOCEPHALA, MgU. 



Frontal stripe black, rather wider than the sides of frontalia, which are grey, 

 with dark reflections ; face white ; antennae grey ; arista long and pubescent, with 

 basal third thickened ; palpi yellow ; thorax grey, with three wide dorsal black 

 stripes, and three post-sutural outer dorso-central bristles ; scutellum grey ; abdo- 

 men black, with the front part of the segments bordered by wide interrupted grey 

 bands, last segment quite grey ; middle segments with both marginal and discal 

 setse, the first and second somewiiat translucent and rufous on their under-surfaces 

 in the male ; alulse and halteres yellow ; wings grey, with yellow roots, having the 

 fourth vein bent at a sharp angle, and sometimes furnished with a short appendix ; 

 legs piceous or black. Rare ; I have two specimens, which I found in the late F. 

 Walker's collection. 



P. NIGEA, DsV. 



P. leucocephila , var. End. 



This species differs from the former by having the abdomen black, glabrous, and 

 without grey bands ; by the absence of discal setae on the segments ; by the wings 

 being without stalks, the cell being closed at the costa ; by the apical cross vein 

 being more oblique, owing to the fourth vein being bent at a more obtuse angle ; 

 by the absence of cubital appendix ; and by the outer cross vein, wliich is oblique 

 and sinuous, being placed rather nearer to the bend of the fourth vein. Rare ; I 

 captured a single specimen in June, 1878, at Sandy, in Bedfordshire. 



42.— LEUCOSTOMA, Mgn.,;?. Zeii.,p. et Schnr. 

 PSALIDA, Rnd. 



This, the last of the group of small genera with closed first pos- 

 terior wing-cells and short antennae, differs from all the rest by having 

 unusually large alulae, and the anal segments of the female armed with 

 forceps or claspers. I have followed Schiner in confining it to the 

 species having these characters, referring several others which were 

 included in this genus by Meigen and Zetterstedt to that of Clista 

 or Phyto. 



Gen. ch. — Frontalia narrow in the male, but wide in the female ; 

 eyes nude ; antennae short, with the third joint a little longer than the 

 second ; cheeks narrow and bare ; facialia nude ; palpi slightly clavate ; 

 abdomen short, thick, and fusiform, or spindle-shaped, without discal 

 setae, and armed with forceps at the end in the female ; wings with a 

 rather long cell-stalk (about two-thirds of the length of the outer 

 cross vein), and with the hinder transverse vein nearly centrally placed. 



L. SIMPLEX, Fin. 



Frontal si ripe l>Iiick, and nitlior narrower than the sides of the frontalia, which 

 are black behind and grey in front; face glistening white, with dark reflections j 



