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MR.  R.  OWEN  ON  THE  OSTEOLOGY  OF 
linger  in  length,  and  is  as  slender  and  weak  as  it  is  short.  The  little  finger  is  also 
shorter,  as  compared  with  the  other  fingers,  than  in  the  human  subject.  The  meta- 
carpal bones  are  chiefly  remarkable  for  their  length  ;  the  phalanges  both  for  their  length 
and  their  anterior  curvature.  The  hand  is  thus  admirably  formed  for  clasping  the  thick 
boughs  of  forest  trees.  The  ridges  on  the  sides  of  the  anterior  surface  of  the  first  and 
second  phalanges  are  well  developed  to  afford  attachment  to  the  fascicE,  which  restrain  the 
starting  of  the  flexor  tendons  during  the  powerful  actions  of  the  muscles  of  the  fore  arm. 
§  2.  Osteology  of  the  young  Chimpanzee. 
In  consequence  of  the  early  period  at  which  the  brain  acquires  its  full  size,  the 
cranial  portion  of  the  skull  of  the  young  Chimpanzee  greatly  preponderates  over  the 
facial  or  maxillary  part  when  the  small  deciduous  teeth  only  are  developed.  At  that 
period,  therefore,  it  proportionally  approximates  towards  the  human  form :  the  facial 
angle  is  more  open;  the  occipital  foramen  is  more  central,  and  its  plane  more  hori- 
zontal ;  the  slender  zygomata,  as  seen  from  below,  are  confined  to  the  anterior  moiety  of 
the  skull ;  and  altogether  the  resemblance  to  the  human  cranium  is  startlingly  close. 
The  difference,  on  the  other  hand,  between  the  young  and  the  old  skulls  is  such,  that 
a  naturalist,  unaware  of  the  changes  of  form  which  the  jaws  undergo  as  they  acquire 
their  permanent  set  of  teeth,  might  fail  to  recognise  them  as  belonging  to  the  same  spe- 
cies, and  might  still  entertain  doubts  as  to  the  specific  identity  subsisting  between  the 
baboon-like  skull  of  the  adult  and  the  anthropoid  one  of  the  young  Chimpanzee,  which 
he  had  previously  been  accustomed  to  consider  as  characteristic  of  the  species.  These 
doubts,  which  I  entertained  myself  on  the  first  inspection  of  the  adult  skeleton,  were, 
however,  in  a  great  degree  removed  by  perceiving  the  correspondence  which  prevailed  in 
the  two  skeletons  in  the  forms  and  proportions  of  the  extremities,  the  number  of  vertebra 
and  ribs,  the  structure  of  the  sternum  and  scapula,  &c.  But  to  derive  further  confirmation 
of  their  identity,  I  compared  the  crowns  of  the  permanent  teeth  ^  which  were  lodged  within 
the  jaws  of  the  young  Chimpanzee,  with  those  which  had  replaced  the  deciduous  set  in 
the  adult  skull.  The  resemblance  in  point  of  figure  and  size  was  exact,  and  showed  that 
the  Pygmy  of  Tyson  must  ultimately  acquire  teeth  which  would  necessarily  induce  those 
changes  of  form  in  the  jaws  upon  which  the  differences  in  question  chiefly  depended. 
The  germs  of  the  permanent  teeth  are  placed  with  singular  irregularity  within  the 
jaws ;  the  second  incisor  is  situated  directly  behind  the  first ;  and  the  apex  of  the 
crown  of  the  laniary  is  lodged  deep  in  the  jaws,  below  the  first  bicuspis.  Both  bicuspides 
are,  however,  lodged  conveniently  below  the  crowns  of  the  deciduous  molares.  Their 
crowns  were  completely  formed,  and  the  first  true  molar  had  taken  its  place  in  the  jaw 
in  the  specimen  examined,  but  its  fangs  were  open  and  incomplete.  The  crown  of  the 
second  molar  was  completely  formed,  and  corresponded  to  the  dimensions  of  the  second 
molar  in  the  adult  skull :  the  germ  of  the  third  molar  was  not  yet  apparent.    The  suc- 
'  See  Plates  LI.  and  LIL,  a,  b,  c,  d,  e,f,  g. 
