Chap. V. ON THE EFFECTS OF DISUSE. 171 



specimens of pouters, trumpeters, swallows, roller-tumblers (like- 

 wise observed in this breed by Mr. Brent), and in a lesser degree 

 in other feather-footed pigeons. 



The feet of the smaller and larger breeds are of course much 

 smaller or larger than those of the rock-pigeon ; but the scutelise 

 or scales covering the toes and tarsi have not only decreased or 

 increased in size, but likewise in number. To give a single in- 

 stance, I have counted eight scutellse on the hind toe of a runt, 

 and only five on that of a short-faced tumbler. With birds in 

 a state of nature the number of the scutellse on the feet is 

 usually a constant character. The length of the feet and the 

 length of the beak apparently stand in correlation ; but as 

 disuse apparently has affected the size of the feet, this case may 

 come under the following discussion. 



On the Effects of Disuse. — In the following discussion on the 

 relative proportions of the feet, sternum, furcula, scapulae, 

 and wings, I may premise, in order to give some confidence to. 

 the reader, that my measurements were all made in the same 

 manner, and that all the measurements of the external parts 

 were made without the least intention of applying them to the 

 following purpose. 



I measured most of the birds which came into my possession, from the 

 feathered base of the beak (the length of beak itself being so variable) 

 to the end of the tail, and to the oil-gland, but unfortunately (except in 

 a few cases) not to the root of the tail ; I measured each bird from the 

 extreme tip to tip of wing ; and the length of the terminal folded part of 

 the wing, from the extremity of the primaries to the joint of the radius 

 I measured the feet without the claws, from the end of the middle toe 

 to the end of the hind toe ; and the tarsus together with the middle toe. 

 I have taken in every case the mean measurement of two wild rock-pigeons 

 from the Shetland Islands, as the standard of comparison. The following- 

 table shows the actual length of the feet in each bird ; and the difference 

 between the length which the feet ought to have had according to the size 

 of body of each, in comparison with the size of body and length of feet 

 of the rock-pigeon, calculated (with a few specified exceptions) by the 

 standard of the length of the body from the base of the beak to the oil-gland. 

 I have preferred this standard, owing to the variability of the length of tail. 

 But I have made similar calculations, taking as the standard the length 

 from tip to tip of wing, and likewise in most cases from the base of the 

 beak to the end of the tail ; and the result has always been closely similar. 

 To give an example : the first bird in the table, being a short-faced tumbler, 



