THE  CHIMPANZEE  AND  ORANG  UTAN. 
357 
descending  angle  of  the  parietal,  and  separates  the  frontal  from  the  temporal  bone,  as 
in  Man.  This  is  one  of  the  few  osteological  differences  in  which  the  Orang  has  a  closer 
approximation  to  the  human  structure  than  the  Chimpanzee^.  In  a  younger  specimen 
of  the  adult  cranium  of  the  Orang  I  observed  that  the  additamentum  sutures  lambdoidalis 
was  still  visible  on  either  side,  but  the  remainder  of  the  sutures,  with  the  exception  of 
those  first  mentioned,  were  obliterated. 
The  occipital /oramew  approaches,  in  its  figure,  position,  and  aspect,  nearer  to  that  of 
the  lower  Mammalia.  Its  plane  forms,  with  a  line  drawn  parallel  to  that  of  the  basilar 
process,  an  angle  varying  in  three  adult  crania  from  15°  to  20°.  The  occipital  condyles 
are  more  closely  approximated  anteriorly  than  in  the  Chimpanzee.  The  anterior  con- 
dyloid foramina  are  double  on  each  side ;  they  have  the  same  relative  position  with 
the  stylo-mastoid  foramina  as  in  the  Chimpanzee ;  the  carotid  foramina  are  situated 
more  posteriorly,  and  are  relatively  smaller ;  the  petrous  portion  of  the  temporal  is 
smaller,  while  the  glenoid  cavity  forms  a  much  larger  proportion  of  the  base  of  the  skull. 
This  articular  cavity,  if  such  it  may  be  called,  presents  a  remarkable  contrast  with  the 
numerous  points  of  resemblance  to  the  Carnivora  observable  in  other  parts  of  the  cra- 
nium :  it  is  a  quadrate  and  almost  flattened  surface,  slightly  concave  in  the  transverse, 
and  slightly  convex  in  the  antero-posterior  directions,  affording  an  interesting  corre- 
spondence with  the  structure  of  the  molar  teeth,  and  being,  together  with  these,  indi- 
cative of  the  vegetable  diet  of  the  animal. 
The  styloid  and  styliform  processes  are  wanting,  as  in  the  Chimpanzee.  The  mastoid 
process  is  represented  by  a  protuberant  ridge  behind  the  auditory  foramen ;  and  its 
cellular  structure  is  visible  from  the  thinness  of  the  external  table  of  the  skull  at  this 
part.  The  ant-auditory  process,  which  protects  the  articulation  of  the  lower  jaw,  is 
more  developed  than  in  the  Chimpanzee ;  the  margins  of  the  auditory  foramina  are 
smoother. 
On  the  bony  palate  the  relative  positions  of  the  foramina  incisiva  correspond  with 
the  increased  development  of  the  laniary  teeth  in  the  Orang,  as  compared  with  the  Chim- 
panzee, and  consequently  deviate  in  a  proportional  degree  from  their  position  in  the  hu- 
man subject.  They  are  situated  upwards  of  an  inch  behind  the  incisor  teeth,  and  two  or 
three  foramina  remain  on  either  side  but  more  anterior,  and  indicate  the  original  sepa- 
ration of  the  incisive  bones.  Small  vascular /orawina  and  grooves  indicate,  in  the  same 
manner,  on  the  anterior  part  of  the  skull,  the  situation  of  the  suture,  or  harmonia, 
which  originally  joined  the  incisive  to  the  maxillary  bones.  The  late  period  at  which  these 
sutures  are  obliterated  forms  an  important  differential  character  between  the  Orang 
'  This  affinity  is  of  less  value  from  the  fact  of  some  of  the  inferior  races  of  Man  occasionally  presenting  the 
same  arrangement  of  these  sutures  as  the  Chimpanzee.  I  have  observed  the  junction  of  the  temporal  with  the 
frontal  bone  in  the  cranium  of  a  native  of  Australia,  and  in  more  than  one  negro.  I  have  also  observed  the 
same  disposition  in  one  out  of  eight  crania  of  the  Simia  Satyrtts :  this  exception  occurs  in  the  skull  of  the 
adult,  of  which  the  entire  skeleton  is  preserved  in  the  Museum  of  the  Royal  College  of  Surgeons. 
VOL.  I.  3  B 
