REE 
ON THE ORIGIN OF THE ARANEIDAL FAUNA 
OF YORKSHIRE. 
WM. FALCONER, 
Slaithwaite, Huddersfield. 
Tue Naturalist who studies plants and animals in a living state 
in their native haunts in order to discover for himself the 
fascinating details of their life history, habits and instincts, 
is often led in consequence of his observations in the field, to 
the consideration of other subjects equally interesting, but 
from their very nature highly speculative in character. In 
none of them is there more scope for surmise and theory than 
in the endeavour to trace the origin of the existing fauna and 
flora of any area, with all the varied and difficult problems 
-which they present as the resultant of the manifold and complex 
influences to which they have been subjected, and to which, 
as living organisms endowed with a certain capacity to adapt 
themselves to the external circumstances of their environment, 
they have responded, through the immense period which has 
elapsed since their creation. 
Such small and economically useless creatures as spiders, 
which keep mostly in strict seclusion and do not therefore 
obtrude themselves upon one’s notice, have never at any time 
been subjected by man to such general and continuous obser- 
vation as the larger, more conspicuous and useful animals and 
plants have been. Neither do their soft bodies adapt them- 
selves to permanent record in the rocks; nevertheless they 
can boast of a considerable antiquity, for out of the countless 
myriads which must have lived, died, and left no sign, some 
250 fossil species, a large proportion of which are referable to 
existing genera, are known to science, the most ancient example 
having been unearthed in Upper Silesia from Carboniferous 
strata of the Paleozoic Epoch. The remains of 180 of them, 
however, were not preserved in the sedimentary rocks, but 
in a much more effective medium for the purpose—amber. 
Had this testimony of the rocks been wanting their world-wide 
distribution and highly specialised form would still have pointed 
to the same conclusion. 
The County of Yorkshire from its geographical position 
and its relatively small size, can only be regarded as a part of a 
very much larger area, and consequently in treating of the 
origin of its spider population, consideration must be given 
not only to the known distributional range of the various 
species outside its limits, but also to the factors which, in the 
past, may have governed it. This has already been done 
to a greater or less extent in the case of the larger organisms, 
the range of which, both in time and space, has been fairly 
fully ascertained, so that it is possible to state with some degree 
1913 Feb. tf. 
