DIPTERA. 503 
Moses Harris was the earliest British author who paid peculiar at- 
tention to the insects of this order, and was the first entomologist whe 
made use of the variations in the nervures of the wings to distinguish 
the groups. More recently, these insects have attracted much at- 
tention abroad; Fallen, in Sweden, having published many memoirs 
respecting them ; Macquart has also published an admirable series of 
monographs upon the Diptera of the North of France, as well as several 
subsequent general works. But it is chiefly to Meigen, whose work 
upon the Diptera of Europe extends to six volumes, and to Wiede- 
mann, whose Exotic Diptera occupies two volumes, that we are in- 
debted for the most complete series of descriptions of the species of 
this order, whilst it is to the works of Latreille that we must look alone 
for the more philosophical views relative to the affinities and conse- 
quent relative situation of the various families of Diptera, the preceding 
authors having implicitly followed him in his modes of distribution. 
The natural classification of the Diptera is attended with great 
difficulty, resulting from the difference in value which may be attached 
to the characters respectively derived from the structure of the an- 
tenn and trophi, and the nature of the transformations; hence we 
find that Latreille, in many of his works, has adopted various plans 
of arrangement, and has likewise suggested others, varying according 
to the different rank supposed to be possessed by either of these prin- 
cipal characters. Thus, in the “ Genera Crustaceorum,” the antennz 
are first employed, and thus we have the Stratiomidee, in consequence 
of their multi-articulate antenne, but which have a coarctate pupa, 
and a mouth furnished with two or at most four setse, introduced be- 
tween the Tipularize and Tabanii, which last have an incomplete pupa 
like the Tipularize and a more complete mouth. In a note, however, in 
the same work there is another arrangement proposed, chiefly founded 
on the structure of the mouth *; and here we have the Tabanii brought 
into contact with the Tipulariaz, whilst the Stratiomide are removed 
* M. Macquart has nearly adopted this proposed arrangement, without acknow- 
ledgment, in his Suites d Buffon, as follows ; — 
Div. 1. Nemocera (composed of Culex and Tipula). 
Div. 2. Bracuocera,. 
Subdiv. 1. Hexacheta, with six sete in the mouth (Tabanus). 
Subdiv. 2. Tetracheta, with four sete, composed of three families — A, Notacan- 
tha (Stratiomys, &e.), B. Tanystoma ( Asilus, Empis, Bombylius, &e.), and 
C. Brachystoma (Rhagio, Dolichopus, Syrphus, &c. ). 
Subdiy. 3. Dicheta (composed of the Athericera and Pupipara of Latreille), 
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