CLASSIFICATION. i 



are shed, and fresh ones take their place, either over a part or the Avhole of 

 the body. The change frequently or generally results in considerable differ- 

 ences of color, constituting the "seasonal plumages" of so many birds, 

 "which, in the same bird, may change from black to white even, from plain 

 to variegated, from dull to brilliant. But birds also change colors, by actual 

 alteration in the tints of the feathers themselves, and by gaining new ones 

 without losing any old ones. The generalization may be made, that when 

 the sexes are strikingly different in color, the young at first resemble the 

 female ; but when the old birds are alike, the young are different from 

 either. When the seasonal changes are great, the young resemble the fall 

 plumage of the old. When the old birds of two different species of the 

 same genus are strikingly alike, the young of both are usually intermediate 

 between them, and difterent from either. 



Besides being the most highly developed, most complex, wonderfully^ per- 

 fect and beautiful kind of tegumentary outgrowth ; besides fulfilling the 

 obvious design of covering and protecting the body, the plumage has its 



§ 11. Peculiar Office : that of accomplishing the act of flying. For 

 all vertebrates, except birds, that progress thi-ongh the air — the flying-fish 

 with its enlarged pectoral fins; the flying reptile (Draco volans) with its 

 skinny parachute; the flying mammal (bat) with its great webbed fingers — 

 accomplish aerial locomotion by means of tegumentary expcmsions. Birds, 

 alone, fly with tegumentary outgrowths, or appendages. 



SECT. II. An allusion to the Classification of Birds — Taxon- 

 omy — Structure — Characters — Groups of Different Grades — 

 Types and Aberrations — Equivalency — Analogy and Affinity 

 — Example. 



Seeing what a bird is, and how distinguished from other animals, our 

 next business is to find out how birds are distinguished from each other ; 

 when we shall have the material for 



§ 12. Classification, a prime object of ornithology, without which, 

 birds, however pleasing they are to the senses, do not satisfy the mind, 

 which always strives to make orderly disposition of things, and so discover 

 their mutual relations and dependencies. Classification presupposes that 

 there are such relations, as results of the operation of fixed inevitable law ; 

 it is, therefore, 



§ 13. Taxonomy (Gr. taxis, arrangement, and nomos, law), or the ra- 

 tional, lawful disposition of observed facts. Just as taxidermy is the art 

 of fixing a bird's skin in a natural manner, so taxonomy is the science of 

 arranging birds themselves in a natural manner, according to the rules that, 

 to the best of our knowledge and belief, are deducible from examination of 

 their 



§ 14. Structure : The physical constitution of a bird ; all the material 

 constituents of a bird, and the way its parts or organs are put together. 



