1870.] Rev. S. Haughton on Animal Mechanics. 



361 



The foregoing animals all realize the typical idea of a true foot, with a 

 variable amount of friction at the ankle-joint ; this friction disappearing 

 altogether in the Boomer Kangaroo, whose method of progression realizes 

 absolute mechanical perfection, as no force whatever is consumed by the 

 friction of the flexor tendons at the heel. 



The only animals whose feet deviated from the typical foot were three, 

 viz. Alligator, Common Porcupine, and Phalanger. In these animals the 

 foot has the mechanical action of a hand, or grasping organ ; and the 

 flexor tendons above the ankle exceeded those below the ankle by the 

 following amounts : — 



per cent. 



1. Alligator 11-5 



2. Common Porcupine 20*0 



3. Phalanger 29*2 



In the case of the flexor tendons of the hand, I obtained the following 

 results : — 



Table II. Friction of Deep Flexor Tendons of Hand. (Cross section of 

 muscle tendons greater than cross section of finger tendons.) 



Amount of 

 friction, 

 per cent. 



1. Common Porcupine .... 710 



2. Sooty Mangaby 49 '2 



3. Nemestrine Macaque, ... 40'7 



4. Capuchin Monkey .... 35 '3 



5. Yirginian Bear 35*0 



6. European Wolf 31 -4 



7. Japanese Bear 30*6 



Amount of 

 friction, 

 per cent. 



8. Negro-Monkey 2 7 4 



9. Spider-Monkey ...... 26*5 



10. Bengal Tiger 22*7 



11. Common Fox 20 '7 



12. Pyrenean Mastiff .... 7«0 



13. Goat 0-0 



It will be observed that the fore foot of the Goat, regarded simply as an 

 orrgan of locomotion, attains a perfection comparable with that of the 

 hind foot of the Kangaroo, no force being lost by friction at the wrist- 

 joint. 



The only animal in which I found a departure from the typical hand 

 was the Llama, in which the flexor tendons of the fingers exceed the flexor 

 tendon above the wrist by 14 "4 per cent. 



The bearing of the foregoing results on the habits of locomotion of the 

 several animals will suggest themselves at once to naturalists who have 

 carefully studied those habits. I shall merely add that the subject admits 

 of being carried into the details of the separate or combined actions of the 

 several fingers and toes, and that the habits of various kinds of monkeys 

 in the use of certain combinations of fingers or toes may be explained 

 satisfactorily by the minute study of the arrangement and several strengths 

 of the various flexor tendons distributed to the fingers or toes. 



