[Annals N. Y. Acad. Sciences, Vol. XXII, pp. 267-294, PI. XXXIV. 

 18 October, 1912] 



NOTES ON THE PEINCIPLES OF QUADKITPEDAL LOCOMO- 

 TION AND ON THE MECHANISM OF THE 

 LIMBS IN HOOFED ANIMALS 



By William K. Gregory 



CONTENTS 



Page 



Introduction 268 



Limbs regarded as compound levers 269 



Evolutionary stages of quadrupedal locomotion 270 



Factors of long distance travelling power in ungulates 270 



Endurance 271 



Adaptations for minimizing waste of energy 271 



Momentum 271 



Propulsion and the center of gravity 272 



Sinuous movement of the body in running 272 



Spiral configuration of limb bones and articular surfaces 273 



Lost motion 273 



Pendulum action of the limbs 273 



Speed 273 



Length of stride 274 



Length of limb 274 



Angle of stride 274 



Acceleration increment, of stride due to ballistic power of limbs .... 274 



Rapidity of stride 276 



Mechanical and physiological relations of "power" and "speed" in the loco- 

 motive apparatus 276 



Contractile force of locomotive muscles 276 



Augmented by "hold and let go" arrangements 277 



Amount of contraction 277 



The "angle of insertion" and the principle of the parallelogram of forces. 277 



Relations of speed of movement and angle of insertion 279 



Variableness of the rotation component : . . . 279 



"Moment of Resistance" and "Diminishing Load" 280 



Summary of mechanical and psychic factors in power and speed 281 



Application of the foregoing principles to the study of the limbs of ungu- 

 lates 282 



Functional significance of the angulation of the limbs 282 



Mechanics of the foot in graviportal and cursorial types . : 283 



Metatarso-f einoral ratios 284 



Other adaptive contrasts in the feet 287 



Graviportal and cursorial types of tibia 288 



Graviportal and cursorial types of femur 290 



Graviportal and cursorial types of pelvis 292 



Graviportal and cursorial types of fore limb 293 



Diagnostic vs. convergent evolution values of limb ratios 294 



Comparative tabic of limb ratios . . . : Facing page 294 



(267) 



