124 



fNoveniV>er, 



n. lERITANS, Fall. 

 This common species abounds evei-ywhere in England ; the females swarming 

 in woody places, especially in warm damp weather, when they cause much annoyance 

 both to horses and men. Macquart confounded this species with the M. meteorica 

 of Linnffius, which is a very difPerent and much less common species, at least in 

 Britain. II. irritans may be distinguished from all the other species in this genus 

 by having the arista sub-plumose (not merely tomentose) ; the middle metatarsi of 

 the males pectinated beneath with thick-set strong bri.stles ; and the posterior tibise 

 (which, as well as the posterior femora, are somewhat elongated and curved) ciliated 

 at the apices with a small tuft of soft hairs. 



' H. DENTIPES, Fab. 

 This species, like the last, is exceedingly common ; it is distinguished, together 

 with the two following species (to both of which it is closely allied), from the others 

 p- 2 in this section by having the extremities of the third 



and fourth longitudinal veins of the wings strongly 

 convergent (Fig. 2). The males of U. dentipes may 

 also be known from the others by the posterior tibia? 

 being somewhat curved, and furnished at their apices 

 on the inner sides with a callosity or tubercle covered 

 with short adpressed hairs ; the anterior tibiae also are ciliated witli a small tuft of 

 hairs on their under-surfaces toward their fore part ; the middle tibiae are armed 

 along their whole external surfaces with a number of very minute erect bristles of 

 even lengths, arranged irregularly in several rows, giving a peculiar appearance under 

 a powerful lens, as if the side of the limb was covered with a " chevaux de frise ;" 

 and lastly, the abdomen is tessellated with white reflections. 



H. PALiESTEICA, Mcig. 

 This species, often confounded with the former, is rare, and has never been 

 characteristically described. It bears a great general resemblance to H. dentipes, 

 from which it differs in the following points : the posterior tibiaj are less curved, 

 and have no callosity at the apex ; the anterior tibise are without the tufts of hair 

 on their under-surfaces ; the middle tibite are ciliated along their outer sides with 

 short curved hairs, which are not erect, but incumbent or imbricated over each 

 other ; and the abdomen is of an uniform grey colour, with a narrow dorsal stripe. 



H. METEOEICA, Lill. 

 This little species, though abundant on the continent, is not of very common 

 occurrence in England. The males are black, usually with fuliginous wings ; have 

 black halteres, and two rather long sharp teeth at the ends of the anterior femora. 



H. AEMiPEs, Fab. 

 Two species have been mixed together under this name, but the true armipes 

 may be distinguished from its congener, which I have named S.fasciculata, by the 

 following characters : the anterior femora have two teeth on their under-surfaces, 

 one much larger than the other, the smaller of which has been overlooked by most 

 authors, with the exception of Macquart, who mentions it in his description of H. 

 /loccosa ; there is a single long, straight, blunt spine (or rather bristle) in the middle 



