THE  CHIMPANZEE  AND  ORANG  UTAN, 
363 
the  spinal  canal,  which  is  pecuHar  to  five,  leaving  three  not  so  perforated  for  the  coccyx. 
Camper,  who  appears  to  have  reckoned  those  vertebra  only  as  sacral  which  transfer  the 
weight  of  the  trunk  upon  the  pelvic  arch,  allows  only  three  sacral  vertehrcB  to  the  Orang, 
and  counts  the  rest  as  coccygeal,  omitting,  however,  the  last,  and  thus  making  only 
seven  false  vertebrae,  which  is  one  short  of  the  true  number  in  the  Orang. 
The  coccygeal  vertebra  are  anchylosed  together,  but  not  with  the  sacrum,  in  the  adult. 
The  ilia  are  rather  more  expanded  than  in  the  Chimpanzee,  but  are  flatter.  The  ischia 
are  less  extended  outwardly,  so  that  the  lower  part  of  the  pelvis  is  narrower,  correspond- 
ing with  the  small  size  of  the  lower  extremities.  Both  the  ischia  and  ossa  pubis  re- 
semble those  of  the  Chimpanzee  in  their  more  elongated  form,  and  the  whole  pelvis 
equally  deviates  from  the  Bimanous  type  in  its  position  with  regard  to  the  trunk.  The 
spine  of  the  os  pubis  is  well  marked,  but  at  a  greater  distance  from  the  symphysis  than 
in  the  human  subject.  The  form  of  the  superior  aperture  of  the  pelvis  is  an  almost 
perfect  oval,  the  antero-posterior  diameter  of  which  is  to  the  transverse  as  3  to  2.  The 
axis  of  the  brim  forms  with  that  of  the  outlet  of  the  pelvis  a  much  more  open  angle 
than  in  the  human  subject,  whence  it  may  be  inferred  that  parturition  is  much  easier 
in  the  Orang. 
The  chest  has  the  same  amplitude  of  development  in  the  Orang  as  in  the  Chimpanzee ; 
it  equals  in  size  that  of  the  human  subject,  and  the  transverse  diameter  is  greater 
than  the  antero-posterior.  The  ribs  are  narrower  and  less  flattened  in  their  form.  The 
cartilages  of  the  first  and  second  pairs  are  proportionally  longer.  The  twelfth  or  last 
rib  is  much  longer,  and  has  a  long  cartilage  at  its  free  extremity. 
The  sternum  is  short,  but  broader  than  in  the  Chimpanzee  :  it  is  composed  below  the 
manubrium,  or  first  bone,  of  a  double  series  of  small  bones,  seven  or  eight  in  number : 
this  structure  is  always  obvious  in  the  Simia  Satyrus,  or  young  animal ;  and  in  the 
skeleton  of  the  Pongo  preserved  in  the  Museum  of  the  College  of  Surgeons,  the  four 
upper  bones  are  still  separate,  and  traces  of  the  harmonia  which  joined  the  four  lov/er 
bones  are  very  evident.  While  in  Paris,  I  carefully  examined  the  sternum  of  the  great 
Pongo  in  the  Museum  of  Comparative  Anatomy  at  the  Garden  of  Plants  :  the  oblique 
transverse  harmonia  resulting  from  the  alternating  position  of  the  original  double  series 
still  remained,  but  the  mesial  harmonia  were  almost  obliterated,  so  that  the  sternum 
would  appear,  to  one  who  had  not  studied  its  composition  in  the  young  Orang,  as  if 
composed  of  a  single  series  of  broad  oblique  ossifications.  In  the  young  Chimpanzee  the 
sternum  is  composed  of  a  single  series  of  bones,  as  in  most  other  Mammalia ;  and  the 
same  structure  is  shown  in  the  adult.  In  the  human  subject,  although  at  the  early 
period  of  ossification  a  single  series  of  ossific  centres  appear,  yet  at  a  later  stage  the 
lower  part  of  the  sternum  is  frequently  seen  to  be  composed  of  a  double  series  of  bones. 
The  clavicles  deviate  from  those  of  the  Chimpanzee  and  of  the  human  subject  in  being 
less  curved :  in  the  skeleton  of  the  Pongo  at  the  College  of  Surgeons  they  are  almost 
straight.    The  scapula  differs  from  that  of  the  Chimpanzee  in  its  greater  breadth,  and 
