of the body is constant for animals of the same length ; 

 there remains the projection of the hind legs. The lat- 

 ter is evidently composed of the sum of the projections 

 of the femur, of the tibia, of the metatarsus, and of the 

 phalanges. Now a glance at Fig. 9 will show that the pro- 

 jection of the femur is almost nothing, as is also that of 

 the phalanges, and that the projection of the leg is de- 

 termined by that of the metatarsus, and especially by that 

 of the tibia. 



Length of tibia, and consequently relative shortness of 

 femur will then be favorable to length of the third step 

 of the gallop. 



CONCLUSIONS. 



The results of this analysis give us a full knowledge of 

 the construction of the sprinter of whom so far we had 

 only studied the fore hand. 



The sprinter will have a relatively short femur and a 

 relatively long tibia. 



A short femur is unfavorable to strength, and requires 

 for putting it into action a more considerable expenditure 

 of force, whence fatigue and limitation of the length of 

 the efifort ; but the muscles which determine this move- 

 ment, fastened as they are to a low and relatively short 

 ischium, give a more sudden propulsive effort and hasten 

 the oscillation of the leg in support. 



The diagonal base, unfavorably affected by bad con- 

 struction of the radii of the fore legs, finds a certain com- 

 pensation in the length of the tibia. Finally, during the 

 rotation of the leg in suspension, the flexors of the thigh 

 and the extensors of the leg. very rapid by reason of their 

 shortness, produce quickly the extension of the tibia, 

 whose length permits the foot to take earlier contact 

 with the ground, which fact shortens the period of sus- 

 pension at the gallop. 



