Spiders. 



389 



concave on the outside and convex within, is formed of more 

 than a dozen layers of the same web which lines the interior, 

 closely laid upon one another, and shaped so that the inner 

 layers are the broadest, the outer being gradually less in 

 diameter, except towards the hinge, which is about an inch 

 long ; and in consequence of all the layers being united there, 

 and prolonged into the tube, it becomes the thickest and 

 strongest part of the structure. The elasticity of the 



Nest of the Mason-Spider. 



A. The nest shut. B. The nest open. C. The spider, Mygale ccementaria. D. The 

 eyes magnified. E, F. Parts of the foot and claw magnified. 



materials, also, gives to this hinge the remarkable peculiarity 

 of acting like a spring, and shutting the door of the nest 

 spontaneously. It is, besides, made to fit so accurately to 

 the aperture, which is composed of similar concentric layers of 

 web, that it is almost impossible to distinguish the joining 

 by the most careful inspection. To gratify curiosity, the 

 door has been opened and shut hundreds of times, without in 



