THE SUNFISH AND THE SPARROIV 61 



the lens, find out what has happened ; now rub from base 

 to tip, and note, under a lens, the result. 



Examine a plucked-out contour feather. How does it 

 differ from the quill feather.'' Can you understand its 

 structure from your study of the quill feather } Note that 

 the tip of the feather is colored and marked while the 

 base is not especially patterned. Why is this .' Ex- 

 amine a down feather. How does it differ in make up 

 from a quill feather .'' From a contour feather .' What 

 is the special use of the down feathers .? Finally, pluck 

 out one of the hair-like thread feathers from the base of 

 the bill and examine it with the lens to determine its 

 structure. 



Make a careful drawing of each of the four kinds of 

 feathers, naming all the parts. 



In classifying birds reference is made in the manuals 

 of classification to differences in the shape and character 

 of many parts of the body and to differences in the plumage 

 of various body-regions. To understand these references 

 it is necessary to become acquainted with the names 

 applied to these various small parts and regions, and so 

 in fig. 34 the names of them all are given. 



Examine the bill or beak. It is composed of an upper 

 and a lower mandible or jaw; the meeting line of the 

 mandibles is called the commissure, and the corner of 

 the mouth is called the rictus; the bristles at the rictus are 

 the rictal bristles; the median ridge of the upper mandible 

 is the culmen, and the median keel of the lower mandible 

 the gonys. Note just above the bill two openings. What 

 are they.' How are they connected with the mouth.? Note 

 the eyes, and at the inner angle of each the delicate nictitat- 

 ing membrane, which can be drawn over the ball. Does 

 the bird have external ears.? The names of the regions of 

 the head which are commonly referred to in describing its 

 markings will be learned from fig. 34. 



