216 
ANIMAL INTELLIGENCE. 
would have either to seek new quarters or to adapt the nest to 
its altered position, and make an opening and door at the ex- 
posed end. In order to try whether one of these spiders would 
do this, Mr. Saunders placed a nest, with its occupant inside, 
upside down in a tiower-pot. After the lapse of ten days a new 
door was made, exactly as he had conjectured it would be, and 
the nest presented two doors like those which he had found at 
first. 
The most remarkable fact connected with these 
animals, if we regard their peculiar instinct from the 
standpoint of the descent theory, is the wide range of 
their geographical distribution. In all quarters of the 
globe species of trap-door spiders are found occurring in 
more or less localised areas ; and as it is improbable that 
so peculiar an instinct should have arisen independently 
in more than one line of descent, we can only conclude 
that the wide dispersion of the species presenting it has 
been subsequent to the origin and perfecting of the in- 
stinct. This conclusion of course necessitates the suppo- 
sition that the instinct must be one of enormous antiquity ; 
and in this connection it is worthy of remark that we 
seem to have independent evidence to show that such is 
the case. It is a principle of evolution that the earlier 
any structure or instinct appears in the development of 
the race, the sooner will it appear in the development of 
the individual ; and read by the light of this principle we 
should conclude, quite apart from all considerations as to 
the wide geographical distribution of trap-door spiders, 
that their instincts — as, indeed, is the case with the 
characteristic instincts of many other species of spiders — 
must be of immense age. Thus, again to quote Mog- 
gridge, — 
It seems to be the rule with spiders generally that the off- 
spring should leave the nest and construct dwellings for them- 
selves when very young. 
Mr. Blackwall, speaking of British spiders, says : — £ Com- 
plicated as the processes are by which these symmetrical nets 
are produced, nevertheless young spiders, acting under the 
influence of instinctive impulse, display, even in their first 
attempts to fabricate them, as consummate skill as the most 
experienced indi viduals.’ 
