24(5 



Mr. Gr. A. Boulenu'er on the Races and 



the many exceptions. The following figure shows how 

 striking these differences between the extremes are : — 



Fie. 4. 



4- 



Hind limbs of var. ridihunda, § from Astrakhan (a), and var. lessoncp, 

 2 from Stow Bedon, Norfolk (b). % nat. size. 



These differences reside in the length of the tibia compared 

 to that of the head and body, to that of the thigh (causing 

 the heels to overlap, to meet, or to fail to meet when the 

 limb is folded at right angles to the body), and to that of the 

 foot ; also in the size and shape of the inner metatarsal 

 tubercle, its basal length being compared to the length of 

 the inner toe (measured from the base of the tubercle). 

 There is another character, not made use of before, derived 

 from the thickness of the crural or tibial part of the limb ; 

 this varies, like other characters, within certain limits, accord- 

 ing to the actual length of the bone and the degree of plump- 

 ness of the individual, but, comparing extreme forms, it 

 will be found that the length of the tibia is usually over 

 3 times its width in the var. ridibunda and under 3 times 

 in the var. lessonw. 



When a large material is carefully examined, it is found, 

 however," that these differences break down for the sharp 

 definition of the various forms; there is considerable over- 

 lap between one form and the one next to it in the series, 

 when the measurements are tabulated, thus precluding rigid 

 definitions : — 



