132 
TWO PRINCIPAL WORKS OF ROBINEAU-DESVOIDY 
want of agreement between them. Meigen's work and his merit 
in using characters borrowed from the venation are mentioned. It 
is shown how Rob.-Desvoidy, having brought together more spe¬ 
cies of Muscidae than all the earlier authors taken together, 
found it necessary to study this group much more in detail 
(“ d’fitudier ce grand genre d'une maniere bien plus minutieuse ”), 
and here the new characters, introduced by Rob.-Desvoidy, are 
enumerated and critically appreciated. 
(Report, p. 6.) Attention is called to the nomenclature adopted 
by Rob.-Desvoidy for the different parts of the head and face; it 
is noticed at the same time that these terms do not quite agree 
with those adopted by earlier authors. The structure of the 
antennae had been studied by Rob.-Desvoidy in great detail, 
and it is acknowledged that he, with perfect reason (“ avec juste 
raison”), considered the arista as the prolongation of the 
antenna (vide Myodaires, p. 11) and not as a mere bristle. 
(Report, p. 7.) The attention given by Rob.-Desvoidy to the 
study of the squamae was something almost new (here the 
Report has a footnote saying that Latreille had already made some 
use of them). Rob.-Desvoidy has introduced the very happy gen¬ 
eralization that the development of the squamae is more or less 
in harmony with the habits of the flies ; that the most active, the 
largest, the most colored, and the high-flying (“ liaut vol ”) 
Muscidae have the largest squamae, while these organs are 
small, or rudimentary, in those species which remain in the 
vicinity of their birthplace. 
Rob.-Desvoidy, with much reason, had also observed that the 
coloration of flies shows a certain relation with their surroundings ; 
that those living in the open air, in the rays of the sun, have more 
brilliant colors than the “ timid species living under the protection 
of rotten mushrooms.” The general structure of the body, that of 
the abdomen and of the ovipositor, are brought into relation with 
the life-habits, etc. 
In a word, the Report shows that the study of Diptera in life 
is the leading idea of Rob.-Desvoidy’s classification. 
Rob.-Desvoidy understood very well “ that everything in an 
organization holds together, and that the necessity of a fact ” (by 
