INTRODUCTION. xxiii 



WELL, Esq. of Sheffield. But now, Reader, let us change the 

 subject. 



The measurements of the specimens described in all the 

 volumes now in your hands, have been taken after the same 

 plan. The length has been measured while the bird was lying 

 flat and extended on its back, from the point of the bill to the 

 tip of the tail, to the extremities of the wings, naturally closed 

 by the sides, and to the end of the longest toe, the legs and 

 feet being stretched to the full length. In Owls and other 

 birds whose heads are large and rounded, the same method 

 has been followed, the measurement not having been taken 

 along the curvature of the parts, as is the practice with other 

 persons. The wings have been measured from the carpal joint 

 or flexure to the tip of the longest quill ; the bills from the 

 base of the ridge to the tip, and from the opening of the 

 mouth to the end of the lower mandible ; the tarsi from joint 

 to joint ; the toes from their base to the root of the claws, and 

 the latter along their back, following the curve. The colours 

 of the bills, eyes, legs, and claws have beeA given from fresh 

 specimens, unless in a few instances where skins only have 

 been seen by me. This is especially the case with the spe- 

 cies received from Mr Nuttall and Dr Townsend. Many 

 specimens of the digestive organs, and other parts, of the birds 

 described, have been deposited in the Museum of the Royal 

 CoUege of Surgeons of Edinburgh, from the President of which 

 I have received letters of thanks. 



Besides the species described in this volume, and portrayed 

 in the fourth volume of my Illustrations, I have presented 

 you with several which reached me in London, and even in 

 Edinburgh, after the " Bu-ds of America " were finished. A 



