1871.] 143 
collections of the Butterflies of the world, and having to investigate the subtle, 
and, as it seems to us, often too finely-drawn, distinctions made by modern 
Entomologists. The question of specific right and the adoption of names must be 
left, to some extent, to individual opinion. The main object of every working 
Entomologist is to find out as readily as possible what others have done before him, 
and to attain this end the things most necessary are Catalogues, such as this of Mr. 
Kirby’s ; for the study of any group of insects without a Catalogue is as difficult as 
would be the acquirement of a language without a dictionary. We can scarcely 
suppose that Mr. Kirby has escaped the commission of errors, perhaps numerous, 
in compiling a work of such extent; but, be that as it may, Lepidopterists will 
not fail to accord to him the credit of having produced a Catalogue which must 
form the ground-work of all succeeding compilations of a like nature. 
We must, however, protest against Mr. Kirby’s dictum, as expressed in his 
preface, that “ the name of every genus which has been previously employed in 
“ either Zoology or Botany should (be) changed;” believing this rule to be most 
pernicious, and that it is sufficient if it be applied to Entomology only; and even 
then we should be sorry to take the initiative in many cases. Also we protest 
against the application by Lepidopterists (including Mr. Kirby) of the term 
“Diurnal” Lepidoptera to Butterflies exclusively, as conveying a false impression ; 
more especially as there are other terms already existing which quite meet the 
strict requirements of the case. 
THE SPECIES OF THE TRICHOPTEROUS GENUS PLECTROCNEMIA. 
BY R. M’LACHLAN, F.L.S. 
In 1864, in vol. i of this Magazine (pp. 25—31), I gave a short 
sketch of the British species pertaiing to Polycentropus and allies, in- 
cluding Plectrocnemia. 1 was then acquainted with only one species 
of the latter genus, and had added nothing to my knowledge when I 
published the “Trichoptera Britannica” in 1865. I then knew of only 
one species as existing in Europe. 
A recent examination of the exponents of the genus in my Con- 
tinental collection, has made evident to me the fact that I have three 
well-marked European species ; and, moreover, that ‘wo of these exist in 
Britain. And yet, in appearance, all three present scarcely appreciable 
differences in their general characters. But certain slight—almost in- 
describable—peculiarities in some individuals, induced me to make a 
closer examination ; and J find that (at any rate for the males) there 
are structural differences in the anal appendices of a most marked 
nature. I proceed to characterize the three species, with the remark 
that it behoves those Entomologists—British and Continental—to 
whom I have distributed types of Zrichoptera, or for whom I have de- 
termined their species, to compare their insects with the diagnoses and 
notes now given. 
