200 
THE ENTOMOLOGIST’S WEEKLY INTELLIGENCER. 
Agabus congener, 
... fontinalis, &c., 
which I shall be glad to exchange for 
good examples of any of my desiderata. 
— D. McGarey, 7, Old Sneddon Street, 
Paisley ; Sept, 1 1 . 
Duplicate Coleoptera. — I have the fol- 
lowing beetles in duplicate, and shall be 
glad to forward them to any gentle- 
man upon receipt of a box and return 
postage : — 
Pogonus chalceus 
Pterostichus piciinanus 
Stomis pumicatus 
Harpalus obsoletus 
... pubescens 
Stenolophus vespertinus 
Bembidium ephippium 
Tachinus subterraneus 
Stenus providus 
Cteniopus sulphurous 
Cassida equestris 
Agelastica halensis. 
— Richard G. Keeley, 1 1 , Sydney 
Terrace, Marlboro’ Road, Chelsea, N.IF. 
EXTERMINATION OF SPECIES. 
To the Editor of the ‘ Intelligencer.' 
Sir, — The question of extermination 
pf species by man’s agency is, to my idea, 
a very interesting point, well worth the 
consideration of all. 
In the case of insects, as far as direct 
causes lie, while admitting the possibility, 
I much doubt the probability, of such an 
occurrence. I am indeed of opinion that 
the thinning out of a few hundreds or 
thousands of a prolific species has a con- 
trary effect — that it is actually advan- 
tageous to the perpetuation of the spe- 
cies. 
Let us take it thus: 10,000 impreg- 
nated females lay an aggregate o{ Jive 
million eggs! or 500 each, which is below 
the mark in some prolific species. It 
cannot be expected in nature that these 
will all undergo their changes, from the 
very fact of the prolixity: probably 
scarcely a five-hundredth part of them 
will reach the perfect state, from various 
causes, among which I mention firstly 
and chiefly atmospheric injhwnces, natural 
enemies, parasites, accident, starvation, 
&c.; lastly (and leastly too), man’s 
slaughter and captures. 
Now, my impression is that had there 
been but a hundred pairs to start from, 
or had the original 10,000 impregnated 
females laid but five eggs a-piece, that 
quite as many perfect insects would be 
produced in a given locality — certainly 
far more in proportion. 
Of course the disappearance of species 
by man’s indirect agency, as the con- 
version of ground into bricks and mortar, 
the tapping of fens, the process of dis- 
foresting, the destruction of food-plant, 
is not only possible but highly pro- 
bable. Yours, &c., 
H. G. Knaggs. 
Notice to Mr. Farren’s Subscribers . — 
I shall be glad if those of my subscribers 
who have not sent their marked lists, and 
also a box for their share or shares, will 
do so, as soon as convenient, to me at 
“ 1, Rose Crescent, Cambridge.” I will 
get a box made for those who do not send 
one, the price of which will be about 
2s. 6d. — W. Fabren. 
Now publishing, 
A NATURAL HISTORY 
of BRITISH MOTHS. By the 
Rev. F. 0. Morris, B.A. With coloured 
Jigures of every Species. In Monthly 
Parts, two shillings each, containing, on 
the average, figures of thirty species. 
Part 16 contains figures of fifty-one 
species, including the whole of the Genus 
E upithecia, with the two newly-discovered 
British species, trisignata and tripunc- 
tata. 
London : Longman & Co., Paternoster 
Row. 
Printed and published by Edward Newman, 
Printer, of No. 9, Devonshire Street, Bishops- 
^ate Without, London, in the County of 
Middlesex. '-Satui'day, September 21, 1861. 
