122 MTCETOPHILID.E. 



Xo better form of primary classification than tliat adopted by 

 Schiner and Winnertz* is at present obtainable, yet it is arbitrary 

 and by no means satisfactory. The main character nsed by them 

 is the relative length of the 1st longitudinal vein to the forking 

 of the 4tli longitudinal. Even if the length of the former is fairly 

 corlstant in most species CI am almost sure it is not so by any 

 means in some species) the latter character is liable to variation 

 in any species, thus nullifying the value of any compai'ative 

 measurements. 



The first group is supposed to contain those species in which 

 the 1st longitudinal vein extends up to or beyond the fork of 

 the 4th vein; the second group, those in which it fails to reach 

 the fork. There are, however, most certainly several species in 

 which sufficient variation occurs to throw out theoretically some 

 individuals, if classified strictly by this character, whilst the 

 commonest species in India, a?, orientalis, lies absolutely on the 

 border line of both groups. Moreover, in a very distinct Oriental 

 species, >S'. rujithorax, Wulp, the 1st longitudinal vein ends 

 above the fork of the 4th vein in the male and distinctly beyond 

 it in the female. But until more reliable characters are set up 

 by specialists best competent to judge them, the present system 

 of classification has to be retained. 



Hchiner's secondary divisionary character, the colour of the 

 halteres, is certainly inapplicable with any degree of reliability to 

 Oriental species, and its value outside a very limited number of 

 forms seems problematical. So many species have various shades 

 of colour between a distinct brown aud yellow that opinions 

 would difi^er widely in their allotment to one or other of the 

 principal groups. 



A i-ather more reliable character seems to be the length of the 

 1st longitudinal vein compared with the length of the wing, such 

 measurements being taken from a line drawn through the base 

 of the wing just before the hiuueral cross-vein. 



Another character which appears consistent in such species in 

 which it occurs, is the presence and number of stiff hairs on the 

 posterior margin of the scutellum, and to a less extent, those 

 along the dorsum of the thorax. These hairs on the scutellum 

 are more frequently found in those species in which the 1st 

 longitudinal vein is short. 



The bulk of the types of the species described in the present 

 work are preserved in the Indian Museum, but it must not be 

 supposed that all the material there in this genus is disposed of, 

 as a number of forms remain, represented by a considerable 

 number of specimens, M'hich may ultimately prove to be of specific 

 value. 



The following table must be received with some caution, pending 



* Winnertz's gigantic monograph published in 1863 is still the standard 

 work and includes descriptions of all the European species known to that date. 



