AVES. 



shovelling small prey from the surface of the ocean. 

 From the modification of the bill and feet, the 

 characters used to divide the Class into Orders are 

 taken. 



Birds, in common with all vertebrate animals, 

 except Mammalia, produce their young in a very 

 incipient state of developement, enclosed within an 

 egg. The egg of this Class, however, differs from 

 others in having a hard brittle shell, composed 

 chiefly of lime, and in being hatched by the heat 

 of the parent's body during sitting. The globular 

 yellow mass within, called the yolk, is gradually 

 absorbed into the bowels of the chick, forming its 

 nutrition. 



In order to economize the animal heat while the 

 mother is sitting, and to prevent its too rapid ab- 

 straction, when she is compelled to leave the eggs, 

 as well as to protect them from accidental injury, 

 that beautiful and admirable piece of workmanship, 

 the result of untaught and unpractised instinct, the 

 nest, is constructed. Various extraneous materials 

 are used for this purpose, and very different degrees 

 of skill and care lavished on the structure. The 

 tender solicitude of the mother bird for her young, 

 in tending and feeding them as long as they con- 

 tinue in the nest, and often for some time after- 

 wards, has afforded the most touching metaphors and 

 symbols in all ages ; and has been used even by 

 God himself to shadow forth his fatherly love and 

 providential care.* 



* Deut. xxxii. 1 1 ; Matt, xxiii. 37. 

 VOL. I. M 



