122 



The Study of Animal Life 



details. Those of the land-crabs (Gecarcinits), the wood- 

 cutting bees (Xylocopa\ the sand-martens, the marmots, the 

 rabbit, the prairie dogs, illustrate this kind of dwelling in 

 various degrees of perfection. 



The male stickleback (Gasterosteus) weaves and glues 



FIG. 27. Swallows (Chelidonaria urbica) and their nest. (After Brehm.) 



the leaves and stems of water-plants ; the minutest mouse 

 (Mus mimitus) twines the leaves of rushes together ; the 

 squirrel makes a rougher nest ; the orang-utan and the 

 chimpanzee construct shelters among the branches ; but the 

 nests of many birds are by far the most perfect works of 

 animal art. 



Of buildings, the swallows' nests by the window, and the 



