THE  CHIMPANZEE  AND  ORANG  UTAN. 
347 
angle  of  the  temporal  joins  the  frontal  and  separates  the  parietal  from  the  sphenoid 
bones,  as  in  six  out  of  seven  skulls  of  the  young  Chimpanzee  which  I  have  examined. 
The  frontal  bone  extends  to  the  middle  of  the  coronal  surface  of  the  cranium  ; 
the  parietals  occupy  the  remainder  of  that  aspect ;  the  squamous  portion  of  the  oc- 
cipital bone,  which  in  the  young  Chimpanzee  encroaches  for  a  small  extent  upon  the 
coronal  surface,  is  in  the  adult  wholly  confined  to  the  inial  or  posterior  region  of  the 
skull :  it  is,  however,  of  considerable  extent,  and  more  convex  than  in  the  Orang, 
and  consequently  more  like  that  of  the  human  subject  ^  The  squamous  portions  of  the 
temporal  bone  extend  over  a  much  less  proportion  of  the  sides  of  the  cranium  than  in 
Man ;  and  their  superior  margin,  instead  of  forming  a  convex  curve,  is  almost  a  straight 
line.  The  mastoid  processes  are  represented  on  either  side  by  a  mere  ridge  of  bone, 
and  the  styloid  processes  by  small  tubercles.  The  condyloid  processes  of  the  occipital 
bone  are  proportionally  smaller  than  in  the  human  subject.  The  foramen  magnum,  in- 
stead of  being  placed  immediately  behind  the  middle  transverse  line  of  the  skull,  as  in 
Man,  is  situated  in  the  middle  of  the  posterior  third  of  the  basis  cranii,  and  its  plane 
is  inclined  upwards  from  the  anterior  margin  at  an  angle  of  5°  from  the  plane  of  the 
basilar  process.  There  are  no  posterior  condyloid  foramina,  but  the  anterior  condyloid 
foramina,  the  foramina  jugularia,  stylomastoidea,  carotica,  spinosa,  and  ovalia,  are  in 
nearly  the  same  relative  positions  as  in  Man  ;  the  principal  difference  is  in  the  greater 
distance  between  the  foramen  caroticum  and  the  foramen  ovale,  in  consequence  of  the 
greater  antero-posterior  extent  of  the  petrous  bone. 
In  consequence  of  the  proximity  of  the  foramen  magnum  to  the  posterior  margin  of 
the  skull,  a  considerable  extent  intervenes  between  it  and  the  posterior  margin  of  the 
bony  palate  ;  this  is  occupied  by  the  before-mentioned  development  of  the  petrous  bones, 
and  a  corresponding  extent  of  the  basilar  element  of  the  occipital.  The  antero-poste- 
rior diameter  of  the  bony  palate  in  like  manner  greatly  exceeds  that  of  the  correspond- 
ing part  of  the  human  skull.  The  zygomatic  arches  are  opposite  the  middle  third  of 
the  skull,  as  seen  from  below,  while  in  the  human  cranium  they  are  included  in  the 
anterior  moiety.  The  form  of  the  basis  cranii  differs  generally  from  the  Bimanous 
and  manifests  the  Quadrumanous  type,  in  its  greater  length,  in  its  flatness,  in  the  small 
extent  of  cranium  behind  the  foramen  magnum,  in  its  contraction  between  the  zygomata, 
and  in  the  large  size  and  especially  the  anterior  development  of  the  bony  palate. 
The  front  view  of  the  skull  of  the  Chimpanzee  impresses  the  spectator  still  more 
strongly  with  its  resemblance  to  that  of  the  Baboon  and  the  inferior  tribes  of  Quadru- 
mana.  The  superciliary  ridges  of  bone  almost  hide  the  cranium  from  view  ;  and  the 
cranial  mass,  instead  of  forming  a  broad  back-ground  to  the  face,  as  in  the  young 
Chimpanzee,  and  as  it  does  in  a  still  greater  degree  in  Man,  is  surpassed  in  breadth 
'  In  two  skulls  of  the  young  Chimpanzee  I  have  observed  an  os  triquetrum  at  the  junction  of  the  sagittal  with 
the  lambdoidal  suture.  Dr.  Traill  notices  a  similar  circumstance  in  the  young  Chimpanzee  dissected  by  him. 
(Wernerian  Transactions,  vol.  iii.  p.  10.) 
