122 The Study of Animal Life part i 



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

 cutting bees (Xylocopn), the sand-martens, the marmots, the 

 rabbit, the prairie dog's, illustrate this kind of dwelling in 

 various degrees of perfection. 



The male stickleback (Gasterosteits) weaves and glues 



Fir,. 27. — Swallows iChflidonaria urbica) and their nest. (After lirelim.) 



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

 (Alits minutus) 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 arc by far the most perfect works of 

 animal art. 



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



