la te Professor Macg Mi v i ni; . 107 



natural groups may be formed by attending exclusively to 

 the exterior of animals, it is only because their internal 

 organisation is presumed to be similar. The external parts 

 afford an index to the internal ; and if we find a bird having 

 a short hooked bill and curved claws, we shall not be wrong 

 in inferring that it has a wide oesophagus and a large mem- 

 branous stomach. The great divisions of zoology can be 

 laid out only by a zootomist ; but the details of the system 

 may occasionally, perhaps frequently, but never with abso- 

 lute certainty, be elaborated by him who regards only the 

 exterior. No rational system of ornithology has ever ap- 

 peared for these two reasons : — Because no system-maker 

 has been equally acquainted with the internal structure, the 

 external parts, and the habits and actions of birds ; and, 

 more especially, because birds have not yet been subjected 

 to a sufficiently minute examination. I have been induced to 

 offer these remarks because I regret that the science has been 

 degraded by having been left entirely in the hands of those 

 who appear to despise, because they have no knowledge of 

 the internal structure of birds ; and I have considered it my 

 duty to impress upon the student the necessity of dissecting 

 with all diligence. Were it possible to cast away all the 

 knowledge already acquired, and commence anew upon the 

 plan of considering birds as admirable specimens of divine 

 workmanship, to be examined in all their details, we should, 

 I believe, be great gainers in real knowledge." — (Introduc- 

 tion, pp. 85, 86.) And again — 



" To acquire a satisfactory knowledge of any bird, one 

 must, in the first place, obtain a general idea of its external 

 appearance, so as not only to be able to distinguish it at 

 sight, but also to know in what respects it resembles others, 

 or differs from them. Then he ought to examine its inte- 

 rior, and more especially its digestive organs, which indicate 

 the nature of its food, the latter necessarily determining its 

 haunts. He now seeks it there, and observes its mode of 

 walking and flying, its favourite places of resort, and its vari- 

 ous actions, listens to its notes, follows it to its nest, which 

 he inspects, and takes note of its migrations or local shift- 

 ings. The food can be detected with accuracy only by open- 



