1802,1 211 



shall describe them as thej occur in the single example which I possess. The point 

 wliich at once distinguishes this species from all the others is the diminutive state 

 of the palpi, which are pale yellow in colour, and very short and small ; the fore- 

 head is slightly prominent, the frontal stripe piceous, and rather narrower than the 

 sides of the frontalia, which are grey with a rufous tinge ; fronto-orbital bristles 

 extending to below the root of tlie arista ; cheeks white and bare ; antennse with 

 third joint thick, and fully six times the length of the second ; arista with basal 

 third thickened ; facialia armed with strong cilise for two-thirds of the way up ; 

 thorax cinereous, with four even black stripes ; scutellum grey ; abdomen cinereous, 

 with posterior margins of segments black ; setae on both disc and margins ; wings 

 with apical cross vein straight, and ending near apex, fourth vein bent in a blunt 

 angle, outer cross vein a little sinuous, and placed rather neai'cr to the angle of the 

 fourth than to the little cross vein ; legs black ; length of specimen about n mm. 

 Very rare. 



P. CiESIFEO^'S, Mcq. 



Chetogena assimUis, End. 

 Forehead prominent, frontal stripe black, and wider than sides of frontalia, 

 which are slate coloured ; cheeks white, with grey reflections, and ciliated wdth a few 

 fine hairs j antennaD with first joint partly rufous, the second and third grey, the 

 latter about four times the length of the former ; arista long, with basal third 

 thickened, and rest extremely slender; palpi yellow, grey and thin at the base, and 

 sub-clavate at the end ; facialia ciliated for about two-thirds of the way up ; thorax 

 covered with dark grey pubescence, and marked with four black stripes of about equal 

 widths, which become indistinct on the hinder portion ; outer dorso-central bristles, 

 three in front and three behind the suture ; scutellum dark grey, sometimes a little 

 rufous at the tip ; abdomen cylindrico-conical, with black and white tessellations, 

 and armed with both discal and marginal setae ; anal segments of male incurved, and 

 sometimes partly rufous ; wings with apical cross veins deeply curved ; legs black, 

 hind tarsi ciliated beneath with yellow hairs. Not uncommon. This species varies 

 very much in size. 



P. ASSiMiLis, Eln. et Schnr. 

 Chetogena grandU^ End. 



Fallen included this, together with the former species, under the name asshnilis, 

 stating that the scutellum was either ferruginous or black ; but the presence of other 

 points besides this show that he mixed two distinct species together ; I shall, there- 

 fore, follow Macquart and Schiner, naming tlie one with the black scutellum P. 

 ccesifrons, and the other P. assimilis. 



This species is usually more robust than P. ccesifrons, the forehead is very promi- 

 nent, the frontal stripe rufescent, the frontalia are wider than in cceaifrons, the ai'ista 

 is thickened nearly to the middle, and has the extremity a little pubescent; the apical 

 cross veins are more oblique and less curved than in ccesifrons, the anal segments of 

 the male are less incurved, the scutellum is almost entirely rufous ; all the other 

 characters are similar to those of the former species. Eare. 



P. UNICOLOE, Fin. 

 Shining black, almost immaculate ; frontal stripe dull brown, rather wider than 



