122 HIGH school zoology. 



.sary to givo to the fcatliei' the requisite strength to encounter 

 the resistance of the air. Tlie feathers, however, are not to l)e 

 merely regarded as organs of llight, but as a warm clothing for 

 the body, necessary to prevent the great loss of heat which 

 would otherwise attend the quick flight and rapid change of air 

 round their owners. 



3. A great many technical terms are necessary in systematic 

 ornithological descrij)tions ; some of these may be studied from 

 Fig. 91. 



Fig. 91— To illustrate the topography and the pluinaire of the Sparrow. 

 (Passer domesticus). (After Thome). 



1, Upper niandilde with nostril ; 2, lower mandible ; 3, ciilmen ; 4, pronys ; 5, lore in 

 front, of the e.\e ; (i, forehead or froiis; 7, crown or vertex; .S, occiput; <), malar or cheek 

 region; 10, throat; 11, breast; 12, abdomen; 13, back; 14, rump with the upper tail 

 coverts; 1.5, rectrices or tail feathers ; Ki, tarsus ; 17, primaries ; l.S, secondary and 

 tertiary remig-es, or wing quills ; 19, alula or bastard wing ; 20, greater ; 21, median and 

 lesser wintf coverts. 



4. Premising then that the plumage is to be regarded as 

 the essential charactei-istic of a bird, let us see, in continuation 

 of the subject of the close of the last chapter, how early 

 the remains of true birds are to be met with in tlie geo- 

 logical history of the earth. Fortunately the feathers an-> 

 well known iu the earliest fossil bird which has been fourd, 



