12 [June, 



the tarsi, which are black ; the fore femora are, however, often darker lliaii the others 

 (piceous). Rare. I have two specimens, one found near Bradford, and the other 

 in Oxfordsliire. 



P. WlNTlIEMI, Meig. 

 This species, like the last, has the alulets comparatively large. It is charac- 

 terized by the abdomen, which is yellow, being marked on the lower edge of each 

 segment by a transverse black line ; the antennae are black in the males, but have 

 the two basal joints pale in the females ; the palpi are yellow ; the thorax is dark 

 grey, the apex of the scutellum and the sides of the thorax being often tinged 

 with yellow, especially in the females ; the transverse veins of the wings are oblique 

 and sinuous. 



P. TEANSVEESA, Fall. 

 This species closely resembles the preceding one ; it differs from it, however, in 

 having the alulets smaller, the scales being only slightly unequal, and in having the 

 external transverse veins of the wings nearly straight and upright ; the femora and 

 tibiae are all yellow in both species. These two flies, which are quite distinct, have 

 been mixed together. Meigen, in his description of P. Winthetni, says, that the ex- 

 ternal transverse veins are straight and upright, but Schiner states that he had 

 examined specimens obtained from Meigen, which all had the veins sinuous ; he, 

 however, thought that there was only one species, and that Fallen's P. transversa 

 was the same as Meigen's P. Winthemi. Rondani also confounded the two species : 

 his description of the male of P. transversa (he does not mention P. Winthemi) ap- 

 plying to that species, while that of the female belongs to P. Winthemi ; for he says 

 of the former, " vena transversa exteriore non rectissima," while he remarks of the 

 latter sex, " alae vena transversa exteriore distincte sinuosa." Both these species 

 are rare, but I possess two males and two females of each. 



P. LATITARSIS, Zett. 



I have not seen a male of this species, which closely I'esembles that of P. trans- 

 versa. The females may be known at once by their having the tarsi of the four 

 posterior legs widely dilated at their extremities. I have two specimens, both cap- 

 tured in Yorkshire. 



P. BicoLOE, Wdm. 



This common species may be considered as the typical one of the group to which 

 it belongs (those with small alulets). I will, therefore, briefly mention its leading 

 features of distinction, so that it may be easy to note the characteristic points by 

 which the following and nearly allied species may be distinguished from it. The 

 forehead and face are somewhat prominent ; the eyes of the male sub-contiguous ; 

 the seta bare ; the antennae usually with all three joints black, but sometimes with 

 the first and second rufous ; the palpi always entirely yellow ; the frontal stripe 

 usually black in the females, and always in the males ; the abdomen of males sub- 

 cylindrical ; all the tarsi and the fore femora black in the males, the tarsi only black 

 in the females. The larvae of this species feed on the leaves of bcveral of the common 

 species of dock (Rume.c), in which they make large blolclics. 



