Chap. V. DESCRIPTION OF BREEDS. 133 



affirm that some domestic races of the rock-pigeon differ fully 

 as much from each other in external characters as do the most 

 distinct natural genera. We may look in vain through the 

 288 known species 4 for a beak so small and conical as that of 

 the short-faced tumbler; for one so broad and short as that 

 of the barb; for one so long, straight, and narrow, with its 

 enormous wattles, as that of the English carrier; for an ex- 

 panded upraised tail like that of the fantail ; or for an oeso- 

 phagus like that of the pouter. I do not for a moment pretend 

 that the domestic races differ from each other in their whole 

 organisation as much as the more distinct natural genera. I 

 refer only to external characters, on which, however, it must 

 be confessed that most genera of birds have been founded. 

 When, in a future chapter, we discuss the principle of selection 

 as followed by man, we shall clearly see why the differences 

 between the domestic races are almost always confined to 

 external, or at least to externally visible, characters. 



Owing to .the amount and gradations of difference between 

 the several breeds, I have found it indispensable in the following 

 classification to rank them under Groups, Races, and Sub-races; 

 to which varieties and sub-varieties, all strictly inheriting their 

 proper characters, must often be added. Even with the indivi- 

 duals of the same sub-variety, when long kept by different 

 fanciers, different strains can sometimes be recognised. There 

 can be no doubt that, if well-characterized forms of the several 

 Races had been found wild, all would have been ranked 

 as distinct species, and several of them would certainly have 

 been placed by ornithologists in distinct genera. A good clas- 

 sification of the various domestic breeds is extremely difficult 

 owing to the manner in which many of the forms graduate into 

 each other; but it is curious how exactly the same difficulties 

 are encountered, and the same rules have to be followed, as in the 

 classification of any natural but difficult group of organic beings. 

 An artificial classification" might be followed which would 

 presen fewer difficulties than a « natural classification ; * but then 

 it woul I interrupt many plain affinities. Extreme forms can 

 readily be defined; but intermediate and troublesome forms 



4 ' Coup d'Oeil sur l'Ordre des Pigeons,' ThU q„*j, i 



par Prince 0. L. Bonaparte, Parian. Lder ^enl " "* ° m "** 



