CHAPTER XVIII. 
BIRDS. 
In birds the skin produces feathers instead of scales 
as in fishes and reptiles. For the study of birds, 
pigeons or English sparrows are easily obtained. Birds 
that are sold for food may be bought at the markets 
and used to illustrate different parts of the work. Living 
birds of some sort should be kept in the laboratory for a 
time while bird-study is going on. Of course nothing 
can take the place of out-of-door work with this class of 
Vertebrata. In answering the following questions a 
living bird should be observed, and stuffed specimens 
of the English sparrow should be in the hands of the 
pupils. 
The Sparrow. Note the shape and color of differ¬ 
ent parts, method of locomotion, both in walking and 
flying, how it eats and drinks and cares for its feathers. 
Do you find eyelids ? Do you find a nictitating 
membrane ? This is a thin membrane at the inner 
corner of the eye. How does the membrane act ? 
Does the bird have ears ? Where are they ? 
Does it have teeth ? How would you describe the 
mouth ? 
Do you find nostrils ? Is the breathing rapid or 
slow ? What do you think about the bird’s tempera¬ 
ture ? 
Does the bird use its wings while walking ? 
What seems to be the use of the tail ? 
Does the bird moult ? 
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