102 
THE WEEKLY ENTOMOLOGIST. 
sect could interbreed, and thus render 
the bias of mutation to a certain ex- 
tent uniform throughout the larger 
area. We have in the difference be- 
tween the parallel forms now exhib- 
ited^ a measure of the effects of sep- 
aration through a very long period of 
time, and when we see however de- 
cided the difference in minor charac- 
teristics how slight is still the separ- 
ation of form from form, we need not 
wonder that no appreciable difference, 
can be found between the figures of 
the Ostrich on ancient Eastern mon- 
uments, and the bird itself still liv- 
ing under the same circumstances of 
climate and food that surrounded it 
3,000 years ago ; and of which fact 
Mr. Westwood makes so strong a 
point in favour of the permanancy of 
species. 
The other specimens exhibited are 
Nebrias and Calathi from Shetland 
Isles. They will all be found to 
differ, to an appreciable extent, from 
specimens captured on the mainland 
of Britain. It is probable that the 
separation of these areas took place at 
a much later date than the epoch of 
the separation of North America from 
Europe. It would therefore have 
been interesting to have compared the 
Lepidoptera of Shetland and Britain, 
only that the distance to which the 
Islands are removed from each other 
is so small as to vitiate the conditions 
of the experiment, by individuals 
occasionally flying over from one area 
to the other. 
I regret I have intermingled in my 
collection specimens of several other 
species of Shetland Geodephaga with 
British caught specimens, as nearly 
all the Geodephaga from those Islands 
exhibit characteristic differences, in 
the shape of the thorax, or of some 
other portion of the structure, disting- 
uishing t hem at once from mainland 
specimens, and affording characters 
sufficiently definite for a Manufac- 
turer of species to found new specific 
names upon. To the Naturalist who 1 
busies himself with nomenclature 
there appears to arise a great practical I 
difficulty from the dis-belief in the 
permanancy of species, but 
does not the Naturalist who 
has full faith in the lastingncss of I 
specific form, spend much of his time I ; 
in trying to ascertain which forms I 
are properly designated as species, I i 
and which as varieties merely ? I 
am inclined to think when once the 1 1: 
fixity of species has ceased to be a L 
matter of faith, as it certainly will I 1 
do sooner or later, principles of no- Ir 
mcnclature will be formed that will 
sweep away that dreadful incubus of I 
synonyms under which we now la. 
labour. 
Let us try to answer the following l y 
questions bearing on the subject. I 
Ought the North American and the I 
European Analogues of each other to 
bear the same or different names? |Rj 
W here a difference of form exists bo- Eli 
tween the individuals inhabiting the L 
two extreme Geographical points of a 
large area, as when a North British Lai 
form can readily be separated from a I'O; 
South British one, ought the extreme L 
and all the intermediate forms to bear Ly, 
