BIRDS. 



423 





barbs project. In the more familiar forms these barbs adhere to each 

 other by little hooklets, so that they form a firm vane or web. At other 

 times these barbs may be more slender and thread-like, and may remain dis- 

 tinct from each other, 

 thus giving rise to the 

 down seen at the base 

 of almost all feathers, 

 and in some' constitut- 

 ing a large proportion 





Fig. 362. — A feather from the tail of a king-bird. 



-V-"" 



or even all of the feather, which is then called a plume. At other times 

 the feathers may consist of a mere thread-like shaft, as in the case of the 

 hairs about the mouth of the night-hawk and similar birds. 



So, too, the names of the feathers on the different parts of the body, 

 especially on the wings and tail, have their own importance from a syste- 

 matic standpoint. In the tail the principal feathers are the tail-feathers, or 

 rectrices ; while the feathers which cover their bases above and below are 

 respectively the upper and under tail-coverts. In the wing there are more 

 features to mention. The long feathers which arise from the hand are 

 called the primaries, and those from the fore arm the secondaries, the last 

 three being termed the tertiaries. Sheathing the bases of these long feath- 

 ers are the upper and under wing-coverts, which are divided into several 

 groups, as shown in the 

 cut, to which reference 

 should be made for de- 

 tails. 



It is to the feathers 

 that the birds owe their 

 beauty. No artist's brush 

 can reproduce some of the 

 brilliant hues. In many 

 cases the feathers have a 

 color of their own ; but in 

 others, and this is true of 

 some of the most bril- 

 liant, the effect is not due 

 to any pigment ; but in- 

 stead is of exactly the 

 same nature as that described on a preceding page as occurring in mother- 

 of-pearl (p. 79). When the birds hatch from the egg, they may either 

 be entirely naked, or they may be covered with down, or, again, they may 

 have true feathers. Some, when hatched, are abundantly able to take care 



Fig. 363. — Wing of a sparrow: Ic, lesser coverts; mc, middle cov- 

 erts; scp, scapulars; gc, greater coverts; t, tertiaries; s, secon- 

 daries; p, primaries; pc, primary coverts; al, ala spuria. 



