[84] 



By G. H. Bryan, B.A. 



Plate XII., Fig. I. 



IN the hotter parts of the earth, the threads spun by spiders are 

 often of considerable strength and toughness, and in some 

 cases are sufficiently strong to strike off the hats of passing 

 travellers or to be woven in looms like the fibres of the silkworm. 



All the trap-door spiders are remarkable for the great strength 

 of their webs, which are used, not for the capture of prey, but for 

 the strengthening of their earthen homes. The silk is mostly 

 yellowish, and so tough that a nest may be removed without any 

 danger of damaging it, and the silk is so strong that, even when 

 the earth has been dried and wholly removed, it will bear a con- 

 siderable strain without breaking, and can be drawn over the 

 finger like a glove. Up to this point the burrow possesses no 

 advantage over that of the bird-spider, being a simple silk-lined 

 tube. But the spider now sets to work at the construction of a 

 door, by which the opening may be not only closed but concealed. 



Guided by instinct, it weaves a circular web rather less than 

 the diameter of the burrow and works into it a quantity of earth. 

 This process is repeated until the spider has constructed a circular 

 plate of alternate layers of web and earth, nearly twice the thick- 

 ness of a penny and slightly conical. Eight or ten layers are 

 employed in the manufacture of the plate. A small portion of 

 this plate is attached to the lining of the burrow, the webs, 

 indeed, of the plate being woven into those of the lining and 

 being a continuation of them. 



The plate, therefore, forms a door with a silken hinge, and so 

 accurately is it constructed that when it is closed the upper 

 surface is exactly level with the ground. It will be seen, therefore, 

 that the aperture is effectually closed ; but there are yet two 

 points in the structure of the trap-door which must be noticed. 

 In the first place, the spider takes care to cover tlie upper surface 

 with earth exactly resembling the soil in which the burrow is sunk, 

 even imitating the irregularity and roughness with astonishing 

 fidelity, and fixing lichens, moss, or even leaves, on it just as the 



