TRAP-DOOR SPIDERS. 127 



by a baby spider is so surprising as almost to exceed 

 belief. 



And yet even tlie most complicated form of nest — 

 namely, that of the branched double-door type — is 

 perfectly reproduced in miniature by these tiny 

 architects, with the upper door, lower door, main 

 tube, and branch (fig. B, Plate IX., p. 98). 



In order to test whether the doors are enlarged or 

 not I measured the surface doors of seven double-door 

 nests and one minute cork door on April 30th, making 

 a careful plan of the terrace wall in which they lay, in 

 order to make sure of finding them again on my return 

 to Mentone in October. 



The following table will show that all were enlarged, 

 the average rate of increase being 1^^ lines in the 

 five and a half months which had elapsed: — 



We can scarcely venture from such limited premises 

 to draw any precise conclusions, but if we suppose 

 that during the entire course of the year the nests 

 increase on an average by about four lines in 

 diameter, and assume that the rate of growth continue 

 the same, the nest of the infant spider, whose surface 

 door measures scarcely a line across, would still 

 require four years to attain the dimensions of some 

 of the largest double-door nests, whose surface doors 

 measure sixteen lines across. 



