186 DOMESTIC PIGEOXS : Chap. V, 



this terminal part from that of the expanded wings, and thns 

 I obtained, with a moderate degree of accuracy, the length of 

 the wings from the ends of the two radii, answering from 

 wrist to wrist in our arms. The wings, thus measured in 

 the same twenty-five birds, now gave a widely different 

 result ; for they were proportionally with those of the rock- 

 pigeon too short in seventeen birds, and in only eight too 

 long. Of these eight birds, five were long-beaked, 39 and this 

 fact perhaps indicates that there is some correlation of the 

 length of the beak with the length of the bones of the wings, 

 in the same manner as with that of the feet and tarsi. The 

 shortening of the humerus and radius in the seventeen birds 

 may probably be attributed to disuse, as in the case of the 

 scapulae and furculum to which the wing-bones are attached ; — 

 the lengthening of the wing-feathers, and consequently the 

 expansion of the wings from tip to tip, being, on the other 

 hand, as completely independent of use and disuse as is the 

 growth of the hair or wool on our long-haired dogs or long- 

 wool led sheep. 



To sum up : we may confidently admit that the length'of 

 the sternum, and frequently the prominence of its crest, the 

 length of the scapulae and furculum, have all been reduced in 

 size in comparison with the same parts in the rock-pigeon. 

 And I presume that this may be attributed to disuse or 

 lessened exercise. The wings, as measured from the ends of 

 the radii, have likewise been generally reduced in length ; 

 but, owing to the increased growth of the wing-feathers, the 

 wings, from tip to tip, are commonly longer than in the rock- 

 pigeon. The feet, as well as the tarsi conjointly with the 

 middle toe, have likewise in most cases become reduced ; and 

 this it is probable has been caused by their lessened use ; but 

 the existence of some sort of correlation between the feet and 

 beak is shown more plainly than the effects of disuse. AVe 



3a It perhaps deserves notice that would, therefore, appear as if, during 



besides these five birds two of the the reduction of their beaks, their 



eight were Barbs, which, as I have wings had retained a little of that 



shown, must be classed in the same excess of length which is characterise 



group with the long-beaked Carriers tic of their nearest relations and pro- 



ami Runts. Barbs may properly be genitors. 

 called short-beaked Carriers. It 



