lOO Cinciiniati Society of Natural History. 



and so discern their mutual relations and dependencies."^- Hence, 

 in order to satisfy this mental craving for a knowledge of the rela" 

 tions of birds to other animals, including man, we must have a 

 Classification, without which there is no science. 



Passing, then, from the consideration of the economic and 

 aesthetic uses of birds, let us take a glance at their Zoological 

 relations ; in other words — at the 



Elements of Systematic Ornithology, 

 which, once mastered will leave you free to pursue the remaining 

 features of the study if you so desire. 



Let it be distinctly understood at the start, that the basis of all 

 zoological classification at the present day is structure, — that is to 

 say, anatomy. 



In order to classify birds, we must define them; that is recog- 

 nize their differences in structure from other animals. This, in the 

 case of recent birds, is not at all difficult to do; briefly stated, a 

 bird is a fcatJicred vertcbratcd aninuil. While this definition is suffi- 

 cient, as already indicated, to seperate all recent birds from reptiles, 

 I. atrachians and fishes, on the one hand, and from mammals on the 

 other, yet there are good grounds for the belief that, were one to 

 possess a complete series of extinct birds, we should have difficulty 

 in distinguishing them by their outer covering alone. In otlier 

 words, we should [)erhaps find animals in which scales and feathers 

 would so intergrade that it would be im])Ossible to say where scales 

 ended and feathers began. 



Hence our definition might be insufficient to define birds from 

 reptiles. It may be stated, in fact, as a general rule, that all Zoo- 

 logical and Botanical definitions are faulty in so far as they mark 

 distinct lines which do not exist in nature, but which are arbitrarily 

 adopted by man for his own convenience. 



A good descriptive definition of birds is thus presented by one 

 of our ablest American ornithologists: — f 



"A bird is an air-breathing, egg laying, warm blooded, feath- 

 ered vertebrate, with two limbs (legs) for walking or swimming, 

 two limbs (wings) for flying or swimming, fixed lungs in a cavity 

 communicating with other air cavities, and one oudet of urinary 

 and generative organs; with {negative characters) no teat^', no teeth^ 

 no fleshy lips, no external fleshy ears, no ((lerfect) epiglottis nor 

 diaphragm; no bladder, no scrotum, no corpus (ollosum. Other 



*Coues"Key to North American liirds." 

 -\ Ibid. 



