DOMESTIC PIGEONS 39 



two arms of the furcula. The porportional width of the 

 gape of mouth, the proportional length of the eyelids, of the 

 orifice of the nostrils, of the tongue (not always in strict 

 correlation with the length of beak), the size of the crop 

 and of the upper part of the oesophagus; the development 

 and abortion of the oil-gland; the number of the primary 

 wing and caudal feathers; the relative length of the wing 

 and tail to each other and to the body; the relative length 

 of the leg and foot; the number of scutellae on the toes, the 

 development of skin between the toes, are all points of struct- 

 ure which are variable. The period at which the perfect 

 plumage is acquired varies, as does the state of the down 

 with which the nestling birds are clothed when hatched. 

 The shape and size of the eggs vary. The manner of flight, 

 and in some breeds the voice and disposition, differs re- 

 markably. Lastly, in certain breeds, the males and females 

 have come to differ in a slight degree in each other. 



Altogether at least a score of pigeons might be chosen, 

 which, if shown to an ornithologist, and he were told that 

 they were wild birds, would certainly be ranked by him 

 as well-defined species. Moreover, I do not believe that any 

 ornithologist would in this case place the English carrier, 

 the short-faced tumbler, the runt, the barb, pouter, and 

 fantail in the same genus; more especially as in each of 

 these breeds several truly inherited sub-breeds, or species, as 

 he would call them, could be shown him. 



Great as are the differences between the breeds of the 

 pigeon, I am fully convinced that the common opinion of 

 naturalists is correct, namely, that all are descended from 

 the rock-pigeon (Columba livia), including under this term 

 several geographical races or sub-species, which differ from 

 each other in the most trifling respects. As several of the 

 reasons which have led me to this belief are in some de- 

 gree applical)le in other cases, I will here briefly give them. 

 If the several breeds are not varieties, and have not pro- 

 ceeded from the rock-pigeon, they must have descended from 

 at least seven or eight aboriginal stocks ; for it is impossible 

 to make the present domestic breeds by the crossing of any 

 lesser number: how, for instance, could a pouter be produced 

 by crossing two breeds unless one of the parent-stocks pes- 



