192 
AERIAL AND TERRESTRIAL DIPTERA 
all, to prevent my name from appearing in science ! Special orders 
had been received from Paris never to quote me! ” 
My critical review of Rob.-Desvoidy’s two principal publica¬ 
tions contains data which, I believe, have not been published before, 
and which nevertheless are indispensable for the proper under¬ 
standing of these works. The pointing out.of the interpolations 
of the editors of the posthumous work of 18G3 will save some 
trouble to conscientious workers of the future. My detailed 
study of Rob.-Desvoidy’s Prefaces has convinced me that this 
author does not deserve the reproach often urged against him 
of having neglected the work of his predecessors, Fallen and 
Meigen. He had done what he could to study and assimilate 
their publications, especially Meigen’s, but he is not to be blamed 
if he failed to achieve the impossible. 
At the end of my paper, “ Two Critical Remarks,” etc. ( Berl . Ent. Zeit., 1893, 
p. I have given a biographical notice of Rob.-Desvoidy. The last 
paragraph of this paper, beginning with the words, “ Rob.-Desvoidy makes on 
me the impression,” etc., must be cancelled, because the disparaging remark on 
his character which it contains is unfounded, and was based upon my, at that time, 
rather superficial knowledge of his works. 
XXIY AERIAL AND TERRESTRIAL DIPTERA 
An attempt to define the adaptive structural modifications produced 
by the two life-habits of Diptera 
A first attempt at a definition of the adaptive characters peculiar 
to the two life-habits of Diptera was made by me in my publica¬ 
tions on Chaetotaxy (“ Nocli ein Paar Worte iiber Chaetotaxie,” etc., 
Wiener Ent. Zeit ., 1882, p. 91 ; 85, 1882; “An Essay on Compara¬ 
tive Chaetotaxy,” etc., Trans. Ent. Soc., London, 1884, p. 499-502 ; 
102, 1884). T he principal application, however, of this contrast, 
as a new aid towards the classification of Diptera, I introduced 
later, in my “Preliminary Notice of a Subdivision of the Suborder 
Orthorrhapha Brachycera on Chaetotactic Principles ” (Berl. Ent. 
Zeit., 1896, p. 365-373; 158, 1897). 
The contrast between the two types of aerial and of terrestrial life- 
habit exists among all the groups of Diptera, although it is more 
