44 MATERIALS FOR A MEMOIR ON 



toes and the body of the foot arise, or tend to arise, from the lower 

 end of the femur, while those which move the leg arise from the 

 pelvis in great part. 



In ungulates (series 682 A, Fig. 5) the entire foot may reach 

 the ground when the animal is in rapid motion. So that the 

 plantigrade expression is possible in an animal as far removed 

 from that type as is the deer from the raccoon. The plantigrade 

 foot is more flexible than the digitigrade ; the distinction between 

 the foot of the deer and that of the raccoon is great, notwithstand- 

 ing the fact that the two feet may under some circumstances do 

 the same work. 



Backward Strain. 



At the end of backward strain of the hind limb the fibula will 

 act as a check to eversion. It is probably one of the uses of the 

 fibula to thus check the eversiou and enable the same bone which 

 affords surfaces of origin to the flexors and everters to slow down 

 the action excited by these very factors. In mammals without 

 distinct participation of the fibula in the composition of the ankle 

 eversion of the foot is less pronounced than in those in which it 

 is present. Thus, in the raccoon, the fibula enters into the joint, 

 and eversion is evident. In those instances in which the ever- 

 sion is well developed yet the fibula is rudimentary, the inversion 

 of the knee is to a corresponding degree emphasized. 



In the backward strain, as seen in the raccoon, the fifth toe 

 leaves the ground before the fourth. The leg is always rigid, 

 but the extent to which the limb lies back of the rump varies. 

 It is less decided in the rack than in other movements, and is not 

 so well developed in some animals as in others. This can be 

 seen in contrasting the movement of the horse and that of the 

 guauaco. For the animal last named, see series 743. 



When an animal retains the hind limb in backward strain and 

 the fore limb in forward strain (the limbs being those of the 

 same side of the body), the trunk on the same side is stretched 

 out to the utmost and the genu-abdominal fold is made tense. 

 (Series 680, Fig. 8.) When the backward strain of the hind limb 

 is associated with the backward strain of the fore limb, the trunk 

 is flexed (if such a term be permitted) and the folds just named are 

 relaxed, and the creases of the skin on the sides of the trunk are 



