Tropidia so nearly resembles Xylota, that I do not think it 

 is natural to place them so far apart as Meigen has done ; in- 

 deed the X. bifasciata of that author has so much the appear- 

 ance of a Tropidia, that I once included it in that genus. The 

 best distinguishing character perhaps is the triangular tooth 

 on the underside of the posterior thighs in Tropidia, which is 

 wanting in Xylota. 



In their habits also, the T. rufomaculata and X. bifasciata 

 are very similar, for they are frequently taken together ; such 

 was the case at Whittlesea Mere, where on flowers in the 

 ditches Mr. Dale and myself found both of them in abun- 

 dance on the 18th of July; and in an excursion along the 

 banks of the river at Wareham, the middle of last June, 

 amongst other interesting insects, we found the T. rufomacu- 

 lata on umbelliferous flowers. 



I find that Meigen had only one specimen of T. milesiformis 

 (a male) to draw his description from, it is therefore very 

 possible that my insect may be synonymous with his ; but as 

 he does not notice the following characters, I feel justified in 

 retaining the name I first used in the * Guide.' The third 

 joint of the antennae is rhomboidal with the angles rounded ; 

 our insect has a whitish grey spot near the base of each wing; 

 in the centre of the 4th abdominal segment the males have 

 an ochreous spot ; the legs are black, the basal portion of the 

 4 anterior tibiae is ochreous, and their tarsi have the penulti- 

 mate joint black. I may further observe, that none of my 

 males are so small as Meigen's ; the female is smaller than the 

 male, and has the base only of the 3rd abdominal segment 

 orange, the wings are nearly transparent, and the 4 anterior 

 tibiae have only black rings towards the apex. 



Scandix Pecten Veneris (Shepherd's Needle or Venus's 

 Comb) is represented in the Plate. ^ 



1 



