122 Mittheil. d. Münchener Ent. Ver. 1881. 
terminology*) of certain parts of the body of the diptera, especially 
of the thorax, and this afforded me an opportunity for developing it. 
In doing this, I purposely preferred a purely conventional, to a homo- 
logical or anatomical nomenclature The latter is much easier to 
praise, than to carry out, being often subject to uncertainty and 
dispute. Thus, what dipterologists hitherto called metanotum , has 
been recently proved to belong to the mesothorax (see the paper of 
Mr. Hammond, in the Journal Linn. Soc. Vol. XV), and if the ar- 
gument is sustained, «we will have either to change the term for 
another, or to continue to use it as a merely conventional term. 
The difficulties of deseriptive entomology are great enough without 
such uncertainty of terms, and it is evident that a conventional ter- 
minology offers more chances of fixity; it may very well exist along- 
side of a homological and anatomical terminology. It was prineipally 
the pleura which required some development of the nomenclature of 
its different regions, and of the sutures which divide them. The 
term pleura itself, being conventional, and not anatomical, I have 
formed the new names of the combinations of this word with other. 
words, indicative of the position of the parts which I intended to name. 
(Mesopleura, Metapleura etc.) 
Bristles easily fall off, and the scars which they leave are not 
always recognizable; in such cases we may sometimes be in doubt, 
whether we have a defective specimen, or an individual aberration, 
before us. Statements about chaetotaxy must therefore be made, as 
well as received, with some caution. 
It is hardly necessary to add, that in this, as im all my previous. 
publications, I adopt Loew’s terminology (explained in the Monogr., 
N. Am. Dipt. Vol. I), as my rule and the basis to start from; only 
I prefer the latin terms to their equivalents in english. Although 
somewhat incomplete and too hastily written, that chapter was com- 
posed by Loew at a late period of his career, and with the full 
benefit of a long experience. I# was a deliberate attempt (as Loew 
says in the introduction to it) to act as an arbiter between the con- 
*) I deliberately prefer terminology, which is consecrated by usage - 
and by the best writers, to horismology, which is not to be found in 
Webster's Dietionary, but in the incorreet form of orismology. 
