BIRDS. 7 



dense and powerful muscles of a hemispherical 

 form, whose flat faces, coated with a thick skin, 

 work over each other like a pair of millstones, 

 and by the aid of small angular stones, sand, &c., 

 swallowed for the purpose, grind down the hardest 

 substances in a very short time. 



With the exception of the beak and the hinder 

 extremities, every part of a Bird is, for the most 

 part, clothed with feathers. The feet are pro- 

 tected by a naked, scaly skin, which in some 

 species extends partly up the leg (tibia). The 

 soles of the toes are covered with a callous modi- 

 fication of this skin, having a granular surface. 

 The plumage of Birds attracts universal admira- 

 tion, for its beautiful fitness for the ends it 

 answers, for its softness, its smoothness, its com- 

 pactness, and for its ever varied hues. The most 

 brilliant colours in nature are lavished upon the 

 feathers of these tenants of the sky ; embellished 

 and set off in some instances with a peculiar 

 reflection that rivals the lustre of burnished 

 metals, or the radiance of precious stones. 



Every one is familiar with the general form of 

 a feather. " When a bird has just left the egg, its 

 covering is a downy kind of hair, several little 

 bundles taking their rise from one common bulb. 

 This is the origin of the future feather. A dark 

 cylinder soon makes its appearance, from the 

 upper extremity of which the sprouting feather 

 emerges, while the lower extremity receives the 



