1876.] 221 



times of the first, segments of the abdomen. The arista is always 

 furnished with distinct, though sometimes short, hairs, and the eyes 

 are naked. 



The number of thoracic bristles in the line beyond the suture 

 (two always being in front) varies from three to four ; they are always 

 constant in number, however in the same species, and are therefore of 

 great specific value, sometimes enabling two otherwise closely allied 

 species to be at once pronounced distinct. 



The flies in this genus are generally smaller, more oblong in 

 shape, and altogether less highly developed than those in the preceding 

 genera. The species are rather numex-ous and difficult to name. 



Htdrophoria. — This genus, of which II. conica is the type, is 

 characterised by the species having plumose antennae, naked eyes, un- 

 spotted oblong or oblong-conic bodies, and subaual genital appendages 

 ill the males. There are four thoracic bristles behind the suture, the 

 last or hindmost of which is always smaller and weaker than the others. 

 This is only a small genus. 



Detmeia. — This genus is very well marked, but only contains a 

 single species, which may at once be recognised by the elongated, bent, 

 and pointed proboscis. This fly, named D. Jiamata, is black and very 

 hairy, has the thoracic bristles arranged two in front and three behind 

 the suture, and has the arista furnished wilh very short hairs, by 

 which character it forms a connecting link to the species in the next 

 sub-division. D. hamata may be found in some places in abundance 

 in the autumn, upon the flowers of the common hawkweed (Ilieracium 

 piloselln) and other CompositcB. 



OxoDO^TiiA and TlYDROXiEA. — These two genera may be mentioned 

 together, as they only differ by having the eyes hairy iu the former 

 and naked or very slightly tomentose in the latter. The species of 

 both may at once be known from all the other AnthomyiidcG by the 

 anterior femora of the males being furnished with one or two teeth 

 near the end. The corresponding tibia? are also mostly notclied. 



The dorsal thoracic bristles are six in number, two iu front and 

 four behind the suture. These two genera form a very natural group. 

 H. mefeorica and other allied species swarm in woody places, and tor- 

 ment horses, especially in damp warm weather. 



Lasiops. — This is a very artificial genus, formed by Meigen to 

 include a few aberrant species which have a n aked arista .- and hairy 

 eyes. One (i. cunctans) closely resembles an Onodontha, only the 

 anterior femora are without teeth ; another is very like a Ilyetodesia, 



