THE  CHIMPANZEE  AND  ORANG  UTAN. 
353 
cility  of  climbing  and  grasping,  render  the  entire  frame  in  a  proportionate  degree  de- 
pendent on  the  upper  extremities  for  support  and  progression.  But  while  the  Chim- 
panzee thus  adheres  to  the  Quadrumanous  character,  and  especially  in  the  curtailed 
proportions  and  detached  opposable  condition  of  the  hallux,  it  must  be  admitted  to  ap- 
proach the  Bimanous  type  in  the  length  and  strength  of  the  hinder  thumb  more  closely 
than  any  of  the  lower  Quadrumana. 
The  agile  and  powerful  locomotive  actions  of  the  Chimpanzee  require  a  proportionally 
ample  development  of  the  respiratory  system,  and  the  size  and  expansion  of  the  thorax 
is  accordingly  a  prominent  character  in  its  skeleton.  The  transverse  exceeds  the  an- 
tero-posterior  diameter  of  this  cavity,  but  not  to  the  same  extent  as  in  Man.  The  ribs 
are  thirteen  in  number  on  each  side,  seven  true  and  six  false.  The  last  two  pairs  are 
proportionally  longer  than  in  Man  ;  and  the  end  of  the  last  rib  is  not  pointed,  but  trun- 
cated for  the  attachment  of  a  cartilage,  which  does  not,  however,  join  the  cartilage  of 
the  rib  above.  The  sternum  is  flattened  from  before  backwards,  but  is  not  so  broad  as 
in  the  Orang :  in  the  adult  specimen  not  only  does  the  harmonia  between  its  body  and 
the  manubrium  remain,  but  those  of  the  four  single  pieces  of  which  the  body  is  itself 
composed  are  still  visible. 
The  clavicle  is  long  and  strong,  so  that  the  shoulders  are  kept  wide  apart :  it  is  not 
straight  as  in  the  Orang,  but  exhibits  the  same  sigmoid  curve  as  in  Man,  though  in  rather 
a  less  degree.  The  scapula,  on  the  other  hand,  recedes  further  from  the  human  type  in 
the  Chimpanzee  than  in  the  Orang,  being  narrower  in  proportion  to  its  length,  and 
having  the  spine  running  more  in  the  direction  of  the  axis  of  the  trunk,  and  situated 
more  towards  the  middle  of  the  scapula,  and  more  perpendicular  to  its  plane.  Tlie 
Ojcromion  process  is  longer  and  narrower  than  in  Man.  The  humerus  very  closely  re- 
sembles that  of  the  human  subject,  but  is  proportionally  longer  and  stronger ;  and  the 
peculiar  twist  is  more  marked,  and  occurs  lower  down  the  bone.  The  distal  articu- 
lating surface  is  formed  so  as  to  allow  of  the  same  advantageous  variety  and  freedom 
of  motion  to  the  bones  of  the  fore  arm  as  in  Man. 
As  the  segments  of  each  limb  recede  from  the  trunk  they  become  subject  to  more 
extensive  and  varied  modifications.  This  is  more  especially  exemplified  in  the  lower 
extremities  of  the  Chimpanzee ;  and  the  bones  of  the  upper  extremity  follow  the  same 
law.  The  disproportionate  length  which  the  humerus  already  presents  becomes  greater 
in  the  bones  of  the  fore  arm ;  and  those  of  the  hand  recede  still  further  from  the  jBi- 
manous  type.  Both  the  radius  and  ulna  are  more  curved  than  in  Man,  and  the  inter- 
osseous space  is,  in  consequence  of  the  direction  of  their  curves,  much  wider. 
The  carpal  bones  have  the  same  number  and  relative  position  as  in  the  human  sub- 
ject ;  but  the  trapezium  and  trapezoides  are  proportionally  smaller,  while  the  os  pisi- 
forme  is  of  larger  dimensions,  being  nearly  equal  to  the  os  magnum. 
The  small  size  of  the  trapezium  evidently  relates  to  the  shortness  of  the  thumb, 
which  it  supports,  and  which  does  not  quite  equal  the  metacarpal  bone  of  the  first 
