ANIMAL LOCOMOTIOX. 43 



Motions essentially the same in all Quadrupeds. 



The motions of all quadruped animals are essentially the same. 

 If a comparison is made between the dog and the raccoon, the 

 contrast between the two forms is at first sight great. But if a 

 careful analysis of the figures be made, it will at once be noticed 

 that the points of variance are in the main due to the rate at 

 which the animal is moving, the gait being the same. The flat, 

 broad, yet exceedingly flexible foot of the raccoon is raised delib- 

 erately from the heel to the toes, and at each stage of the strain, 

 which is coincident with the heel elevation, the graphic expression 

 of the pictures is totally unlike the short, decisive motion of the 

 small and almost digitigrade foot as seen in the dog. (See p. 50.) 

 But the order of the foot-falls is similar in the two animals. 



In like manner contrast may be established between the appear- 

 ance of the foot as it is being carried through the air in prepara- 

 tion for a stroke. When an animal is going at a high rate of 

 speed the succession of the movements of the fore and the hind 

 feet is altered. In slow rates the fore foot remains on the around 

 until the hind foot is in its turn lodged. For an appreciable time 

 both feet remain on the ground nearly at the same spot. This 

 position is well seen in the raccoon (series 744, Figs. 3 and 4) and 

 in the baboon, as well as in the sloth (series 750). It affords a 

 good example of central support. (See p. 3S.) 



But in fast rates the fore foot has left the ground before the 

 hind foot reaches it, so at no moment are the two feet on the 

 ground at the same time. Flat-footed forms are capable of retain- 

 ing the two feet on the ground at the same time without the sacri- 

 fice of speed noted in the small-footed types, such as the soliped 

 and the ungulate are compelled to submit to. 



In the raccoon the fore limb may be, in some positions, used as 

 a balance to prevent the animal being toppled forward. 



Division of Parts of Limbs based upon their' Movements. 



The limb is easily divided into two great parts, — that from the hip 

 to the knee and that from the knee to the toes. The movements 

 for the most part are the to-and-fro motion of that portion of the 

 hind limb placed to the distal side of the knee, and to that part of 

 the fore limb beyond the elbow. The muscles which move the 



