INTRODUCTION. 



Birds form one of the most marked and grand divisions of verte- 

 brated animals, as well as the most lovely group in creation. They 

 are oviparous, red and warm-blooded, feathered bipeds breathing 

 by lungs which are bound by cellular tissue to the inside of the ribs 

 and the sides of the dorsal vertebrae, there is therefore no distinct 

 thoracic cavity, nor free muscular diaphragm. The cells open directly 

 from the bronchial trunks and, though minute, are large compared 

 with the cells of the lungs of quadrupeds. The interior of the bones, 

 by communicating with the cells of the lungs, are respiratory organs, 

 which communicate circuitously with the trachea. The cells which 

 are continued from the lungs into the cavity of the abdomen, extend 

 to the interior of the trunk, appear in the axillae, in the neck, and in 

 the region of the pelvis. In fact, every part is impregnated with the 

 air in which they are destined to move. The young of birds, how- 

 ever, have the interior of their bones filled with a thin serous fluid or 

 marrow, but this is soon displaced by air from the air-cells of the 

 lungs which gains access at the proximal extremities, to the extent 

 necessary for the various species according to their habits and modes 

 of life. Being intended for flight, their external anatomy or those parts 

 generally visible are specially organized for the purpose. The body is 

 covered with feathers, instead of hair or wool, and the two forefeet of 

 mammals are transformed into wings. As in other classes the form of 

 structure of the body and all its various members as well as the modi- 

 fications which these parts assume are discriminating characters which 

 enable the Ornithologist to form conceptions of their respective pecu- 

 liarities. The primary parts of birds, as of all vertebrates, are the head, 

 body and limbs, under which subordinate members may be classed. 

 The head is composed of the bill and the skull. The latter is 

 joined to the body by a neck. The skull is formed of a thin, nearly 

 diaphanous and continuous plate of bone above, with all the cranial bones 

 anchylosed. The occipital is not separated from the parietal bones 

 by a lambdoidal suture, nor is there a sagittal suture to separate the 



