216 AI^IMAL 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 flower-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 individuals.' 



