166 Distribution of Moths of the Sub-Family Bistoninae. 
general trend of the mountain ranges, would spread fanwise, 
until all suitable localities in north and central Europe were 
occupied. But the ice gave it no respite; soon the huge ice 
sheets of northern and western Europe buried the land and, 
except in favoured areas,* all life was banished and forced south- 
ward and eastward, following the great river valleys and the 
general direction of the Central European mountains and our 
species reached (if even in more favourable times, there had not 
been outposts along the foothills of the Carpathians) the Balkan 
area, where it took refuge and finally completed its development. 
That the Balkans formed the centre of dispersal of the species, 
we now know as L. hirtariais absolutely certain, because every 
line of migration, whence it occupied its present station, radiates 
from that point as a centre, as even a casual glance at the map 
will show. 
But why was the Balkan Peninsula the last refuge of the 
species, might be asked ? And why did the species not pass 
eastward into Siberia? That it did reach Asia Minor is clear 
from its present stations in Pontus and Bithynia, from which 
we glean that, when the species reached its maximum south 
easterly extension, such difficult passages as the Dardanelles 
and Bosphorus were non-existent. If it could make progress 
in the difficult country of Asia Minor, why did it not pass into 
Siberia, to the north of the Caspian Sea and occupy the whole of 
the !and, in an ail conquering mass, instead of the narrow wedge 
which strikes now across the Uralsk to Lake Issi Kul 2? Simply 
because the Turkestan colony is recent and, when the species 
was retreating before the oncoming ice, it met a barrier which 
effectually forbade its passage into Asia through the gap between 
the Ural Mountains and the Caspian Sea, and that barrier was a 
long arm from the Arctic Ocean, which, flanking the Ural 
Mountains, connected the Arctic Ocean with the united Caspian 
and Aral Seas. This arm of the sea explains the cccurrence 
of so many Arctic species or species ‘representative’ of Arctic 
species in the Caspian Sea. 
(To be continued). 

-O: 
The New Phytologist, published on March 25th., contains the following 
papers :—On the structure and origin of ‘Cladophora’ Balls, by 
Elizabeth Acton ; Carbon Assimilation, by Ingvar Jérgenson and Walter 
Stiles ; Notes on the Corolla in the Composit:e, by James Small; Marine. 
Fungi Imperfecti, by Ceo. K. Sutherland. 


* It must not be assumed that I believe in the wholesale stamping 
out of animals and plants demanded by ‘whole hogger’  glacialists. 
Our Lusitanian and American elements (and still more the -‘ Atlantean ’ 
elements present in the mosses and liverworts) must have survived. - Be- 
sides, where, at the present day, do we find any area devoid of animals 
and plants ? 
Naturalist 

