32 iJuiy- 



much thickened at the apex in the males ; alulets rather small, but 

 with the scales unequal in size ; wings with the third and fourth longi- 

 tudinal veins parallel or slightly convergent at their extremities, anal 

 vein prolonged to the margin ; legs always black or grey. 



1. PLUviALis, Linn. 



procellaris, Rond. 

 imhrida, Eond. 



2. ALBICINCTA, Fall. 



3. PRATixcoLA, Panz. 



4. RADicuM, Linn. 



vulgaris, R. Desv. 

 brass iccB, Wdm. 



5. STJLCIVENTEIS, Zett. 



6. OCTOGL'TTATA, Zett. 



A. PLUVIALIS, Linn. 

 This common pretty spotted fly varies a good deal, the spots often coalescing so 

 as to alter the design on the thorax and abdomen. Two of the varieties thus pro- 

 duced have been exalted by Eondani into distinct species, but they possess no real 

 specific distinctions. 



A. ALBICINCTA, Fall. 



This little species bears a good deal of resemblance to the last, but, besides being 



very much smaller, differs in having the thorax black, with two white spots on the 



hinder part in front of the scutellum. The abdomen is marked as in A. pluvialis, 



being white with a dentated black band at the base of each segment. Not common. 



A. PRATINCOLA, Pz. 



This species has the abdomen marked in a very similar manner to those of the 

 two preceding ones, but the thorax is jDeculiarly figured, being of a whitish-grey 

 colour, with a single black elongated rhomboidal mark in the centre of the posterior 

 part. It is about the same size as A. alhicincta (about 3 mm., I3 lin.), and is also 

 rare. 



A. RADICUM, Linn. 



This excessively common little fly, which, as its name imparts, feeds in the larva 

 state upon the roots of plants, especially on those of the cabbage tribe, is often con- 

 founded with other species. It may be recognised by its projec.ing epistome ; by 

 the unequal sized scales ; by the thorax being black, and marked in the male by 

 two short, grey, narrow stripes (rather than by three wide black ones, as is usually 

 stated) ; by the rather short, wide, somewhat pointed abdomen, with a longitudinal 

 dorsal black mark, crossed by three transverse straight black lines, extending of an 

 even width to the margins ; and by the third and fourth longitudinal veins of the 

 wings being slightly convergent at their extremities. 



A. SULCIVENTRIS, Zett. 



This species bears a good deal of resemblance to A. radicum, but is less; has 

 the antennae much shorter ; the arista more pubescent ; the thorax without any dis- 

 tinct stripes on the dorsum, only having an irregular white line on each side ; and 

 the abdomen less pointed, and thicker at the apex as well as differently mai-ked ; it 



