GENERAL ANATOMY. 21 



we add to this the great differences in the range of markings and color, even 

 in a single individual, and the great differences between the snmnier and winter 

 habitats, the lengths of migration and the difficulty often experienced in getting 

 suitable molting material, we are not surprised that the fallacy of a color 

 change in a dead structure should have taken such a hold and have been so 

 vigorously supported. One by one the facts brought forward to sui)port the 

 theory have been shown to be due to the other causes, so that few to-day ac- 

 cept the theory of color change in birds without a molt. 



CHAPTER II.* 



GENERAL ANATOMY. 



What is known at the present time of the anatomy of birds would, if 

 collected together, fill a considerable number of volumes, while what we have 

 yet to learn in this field of research would furnish sufficient material that, if 

 printed, would indeed make quite a library. From this the reader will appre- 

 ciate the fact that to condense the knowledge we possess today on this subject 

 into a few pages, the resulting contriliution must obviously form but the 

 merest outline or sketch of this department in the biology of Aves. This 

 then must largely be the nature of the present chapter, though it is believed 

 that even in so limited space the beginner may gain some if \ of at least the 

 rudiments of avian anatomy, while, on the other hand, a ^,ul^.. *o the wise is 

 often sufficient. 



As in the case of all other organized forms, birds hare an anatomy, a 

 characteristic structure, — in other words a definite anatomical structure, — often 

 referred to as their morphology or morphological structure. Avian anatomy 

 or avian morphology, then, takes into consideration the structure of birds, and 

 it may be studied in a variety of ways. In the first place we may study the 

 structure of some single species of the class, confining our researches to it alone, 

 as has often been done in the case of man; in the second place we may investi- 

 gate the anatomy of all the species of some particular genus, or family, or 

 suborder or other group, and compare their characters hiter se; or, finally, 

 we may take into consideration the morphology of all existing birds, as far as 

 we have afay knowledge of it, and contrast the comparable characters with the 

 corresponding structures as they occur in the representatives of the other 

 groups of vertebrated animals. This latter course will bring to light the fact 

 that, notwithstanding the great morphological modifications we shall meet with 



♦The chapter on the Anatomy of Birds is by Dr. R. W. Shufeldt. 



