ANIMAL MECHANICS. 409 



Taking the sums of the muscles in groups, I find the fol- 

 lowing results : — 



Muscular Types of Man and the Quadrumans — Hand. 





Walking. 



Grasping. 



Extending. 



Total 

 weight. 







Per cent. 



Per cent. 



Per cent. 



Uz. av. 



I. 



Man 



16.04 



43.48 



40-48 



12. 03 



2. 



Gorilla, * . . 



17-6.5 



52- 17 



30. 18 



0 98 



3- 



Chimpanzee, . . 



16.38 



49 *4 



34 48 



1. 16 



4- 



Hamadryas, . . 



28.32 



40. 15 



3i-53 



5.58 



5- 



Cynomolgus, . . 



15-54 



53.38 



31.08 



1.48 



6. 



Mandrill, . . . 



'9- J 5 



50. 00 



30.85 



4-44 



7- 



Khesus, . . . 



22.77 



46.68 



3° 55 



3-47 



8. 



Ateles, .... 



16. 24 



54.82 



28. 94 



1.97 



From this Table it appears that the chief muscular peculi- 

 arity of Man's hand consists in the great developement of the 

 extensor muscles ; and on analysing these muscles it will be 

 found that it is the extensors of the wrist that are principally 

 developed. 



Wrist JExtensors of Man and the Quadrumans. 





Extensor 

 carpi ra- 

 dialis (a). 



Extensor 

 carpi ra- 

 dialis (/3). 



Extensor 



carpi 

 ulnaris. 



Total. 







Per cent. 



Per cent. 



Per cent. 



x'er cent. 



I. 



Man, .... 



9- 6 5 



6.48 



5 65 



21.78 



2. 



Gorilla, . . . 



2.56 



5- 12 



4. 60 



12.28 



3- 



Chimpanzee, . 



6. 03 



17 



3-45 



14.65 



4. 



Hamadryas, . . 



5.01 



6.08 



5-55 



16 64 



5- 



Cynomolgus, . . 



3.80 



6-33 



5-4o 



^5-53 



6, 



Mandrill, . . . 



6 30 



5.63 



4 95 



16. 88 



7- 



Ehesus, . . . 



4.61 



7-49 



5.76 



17 86 



8. 



Ateles, .... 



3-55 



5.58 



4. 06 



i3- '9 



The remarkable developement of the extensor muscles of 

 the wrist in Man is probably connected with the corre- 

 sponding developement of the Deltoid muscle in the shoulder, 

 and the combination of both is essential to characteristic 

 human action — such, for example, as stone-throwing and 

 oratorical gestures. 



It is interesting to observe that the Gorilla approaches 



