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MR.  R.  OWEN  ON  THE  OSTEOLOGY  OF 
sition  and  proportions  of  the  teeth,  which  afford  unfaiUng  and  impassable  generic 
distinctions  between  Man  and  the  Ape^. 
To  place  this  proposition  in  the  most  unexceptionable  light,  I  have  selected  the  cra- 
nium of  a  human  idiot,  in  whom  nature  may  be  said  to  have  performed  for  us  the  ex- 
periment of  arresting  the  development  of  the  brain  almost  exactly  at  the  size  which  it 
attains  in  the  Chimpanzee,  and  where  the  intellectual  faculties  were  scarcely  more  deve- 
loped. Yet  no  anatomist  would  hesitate  in  at  once  referring  this  cranium  to  the  human 
species* 
A  detailed  comparison  with  the  cranium  of  the  Chimpanzee  or  Orang  shows  that  all 
those  characters  are  retained  in  the  idiot's  skull  which  constitute  the  differential  features 
of  the  human  structure. 
The  cranial  cavity  extends  downwards  below  the  level  of  the  glenoid  articulatory 
surfaces. 
The  nasal  bones  are  two  in  number,  and  prominent. 
The  jaws  and  teeth  exhibit  the  Bimanous  characters  as  strongly  as  in  the  most  elevated 
of  the  human  race.  The  cuspidati  do  not  project  beyond  the  contiguous  teeth,  and  con- 
sequently there  are  no  interruptions  in  the  dental  series,  as  in  the  Orangs,  where  they 
are  required  to  lodge  the  disproportionate  crowns  of  the  canine  teeth. 
With  respect  to  the  zoological  relations  subsisting  between  the  Chimpanzee  and  Orang, 
the  differences  above  mentioned  warrant  their  being  regarded  as  types  of  two  distinct 
subgenera.  The  characters,  however,  proposed  by  M.  GeofFroy  St.  Hilaire^,  being  de- 
rived from  immature  specimens,  require  to  be  altered. 
Subgenus  Troglodytes. 
Muzzle  long,  truncated  anteriorly ;  strong  supraciliary  ridges,  behind  which  the  fore- 
head recedes  directly  backwards  ;  no  cranial  ridges. 
Facial  angle  35°,  excluding  the  supraciliary  ridges. 
Auricles  large. 
Thirteen  pairs  of  ribs ;  bones  of  the  sternum  in  a  single  row. 
Arms  reaching  below  the  knee-joint. 
Feet  wide  ;  hallux  extending  to  the  second  joint  of  the  adjoining  toe. 
Canines  large,  overpassing  each  other,  the  apices  lodged  in  intervals  of  the  opposite 
teeth. 
'  Perhaps  one  of  the  best  exemplifications  of  the  degree  of  approximation  which  the  Quadrumana  make 
towards  the  human  species,  is  the  position  assigned  by  naturalists  to  the  adult  Orang  before  its  identity  with 
the  immature  Satyrus  was  established.  See  '  Annales  du  Museum,'  torn.  xix.  p.  89  ;  Latreille,  '  Fam.  Nat.  du 
Regne  Animal,'  p.  44  ;  and  Fischer,  '  Synopsis  Mammalium,'  p.  32,  who,  without  entering  into  the  particular 
differences,  observes,  "  Sunt  qui  hanc  speciem  (Simia  Wurmbii)  pro  Sim.  Satyro  adulta  ducant.  Permultse  tamen 
sententiae  isti  repugnare  \ddentur." 
Annales  du  Museum,  tom.  xix.  p.  87. 
