2 SYSTEMATIC ORNITHOLOGY. 



The Science of Ornithology. — The science of ornithology may be 

 divided into three branches — systematic, philosophic, and economic. 

 The systematist aims to classify birds according to what are appar- 

 ently their true relationships. He is the ornithological storekeeper, 

 and having taken an account of stock it is his duty to keep the books 

 of the firm in order. The philosophic ornithologist- accepts as a fact 

 the statement of affairs given him by his fellow-worker the systemat- 

 ist, and tries to explain the wherefore and why. He is a seeker of 

 causes. The economist is of a more practical turn of mind. He is 

 impressed by the incalculable influence which birds exert over our 

 agricultural interests, and the necessity for learning with exactness 

 whether this influence is for good or evil. But let us describe these 

 three departments of scientific ornithology more fully. 



Systematic Ornithology. — The first step in the scientific study of 

 any group of animals is to name and classify them. Orders, families, 

 genera, species, and subspecies are to be described and arranged in 

 what appears to be the most natural manner. Thus all the Perching 

 Birds, for example, are placed in the order Passeres, and this order is 

 divided into numerous families — for instance, the Thrushes or family 

 Turdidce. But how are we to know which are Perching Birds and 

 which of the Perching Birds are Thrushes ? The systematist answers, 

 by studying a bird's structure. Generally speaking, orders and fami- 

 lies are based on skeletal, muscular, and visceral characters which may 

 be termed internal characters. Genera are based on the form of bill, 

 feet, wings, and tail, or on external characters, while species and sub- 

 species are based mainly on color and size. Thus all the members of a 

 family or order agree more or less in their principal internal charac- 

 ters : those of a genus agree in external characters, and the individ- 

 uals of a species or subspecies resemble one another in color and 

 size. 



The object of classification is to aid us in understanding not alone 

 the relationships of one bird to another bird, or of one family or 

 order of birds to another family or order, or even of living to extinct 

 birds, but also to assist us in explaining the relationships of all the 

 classes of the animal and vegetable kingdoms — mammals, birds, rep- 

 tiles, fishes — and thus down the scale to the lowest forms of life. 



This systematic study of the relationships of birds has taught us 

 that they have been evolved from reptilian ancestors. There is much 

 evidence in support of this fact, but the most conclusive is furnished 

 by the discovery in the lithographic slate of Solenhofen. Bavaria, of 

 several specimens of a remarkable fossil, a reptilelike bird, which has 

 been named Archmopteryx lithographica. It is the earliest known 

 direct progenitor of the great class Aves. 



