90 THE LIFE OF A BIRD. 



nest, and this to the flat nest. In the opposite 

 direction, again, the walls of the nest rise upwards, 

 and form a purse-shaped nest ; and higher still until 

 they, over-arching, meet above, when the nest is 

 called dome-shaped. To one or other of these 

 varieties a large number of nests may be reduced ; 

 and in so doing, it is not of course necessary to 

 regard the materials of which they are composed, 

 the external form alone being taken into account. 

 The manner in which the nest is supported in- 

 troduces another means of classifying many nests. 

 While some rest on the ground, or on the branches 

 of a tree, where they are supported by the diverg- 

 ing of the boughs, others are suspended by their 

 rims, and some even hang down swinging in the 

 air ; and these last are called " pensile nests." 

 Nests are also frequently classified according to the 

 method of their construction. Some, for instance, 

 are woven, some are felted, some are sewn, some 

 are plastered, some are loosely thrown together. 

 But there is great need of a systematic classifica- 

 tion being adopted among ornithologists, who at 

 present have no precise rule for the arrangement 

 of the nests of birds. It is, in fact, a matter of 

 surprise that so little attention should have been 



