56 



HOMES WITHOUT HANDS. 



between strata of stone, and so saved themselves from any trouble 

 except scraping and throwing out the loose sand. 



"When, however, thq Sand Martin is unable to find such a 

 situation, it sets to work in a very systematic fashion, trying 

 several successive spots with its beak, until it discovers a suitable 

 locality. It then works in a circular direction, using its legs as 



RAND MAHTi:*. 



a pivot, and by dint of turning round and round, and pecking 

 away as it proceeds, soon chips out a tolerably circular hole. 

 After the bird has lived for some time in the tunnel, the shape 

 of the entrance is much damaged by incessant passing to and 

 fro of the inmates, but while the burrow is still new and un- 

 tenanted, its form is almost cylindrical. In all cases the tunnel 

 slopes gently upwards, so as to prevent the lodgement of rain, 



