﻿6 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  than 
  any 
  cranial 
  characters 
  found 
  by 
  us. 
  In 
  Middle 
  America, 
  for 
  

   example, 
  skulls 
  of 
  vellerosus 
  from 
  Mexico 
  are 
  distinctly 
  narrower, 
  

   with 
  less 
  noticeable 
  widening 
  of 
  the 
  brain 
  case, 
  than 
  those 
  of 
  fana- 
  

   me^isis, 
  but 
  differ 
  little 
  in 
  other 
  respects 
  and 
  despite 
  great 
  differences 
  

   in 
  color 
  are 
  obviously 
  assignable 
  to 
  the 
  same 
  species. 
  Unlike 
  many 
  

   other 
  primates 
  the 
  sexes 
  in 
  the 
  spider 
  monkeys 
  differ 
  little, 
  if 
  at 
  all, 
  

   in 
  size. 
  One 
  of 
  the 
  largest 
  skulls 
  of 
  geoffroyi 
  is 
  that 
  of 
  an 
  old 
  female 
  

   from 
  Lavala, 
  Nicaragua. 
  

  

  For 
  loan 
  of 
  pertinent 
  material 
  our 
  thanks 
  are 
  tendered 
  to 
  the 
  fol- 
  

   lowing: 
  Dr. 
  Thomas 
  Barbour, 
  director, 
  and 
  Barbara 
  Lawrence, 
  Mu- 
  

   seum 
  of 
  Comparative 
  Zoology, 
  Cambridge, 
  Mass.; 
  Dr. 
  Adolph 
  H. 
  

   Schultz, 
  Laboratory 
  of 
  Physical 
  Anthropology, 
  Johns 
  Hopkins 
  

   Medical 
  School, 
  Baltimore, 
  Md. 
  ; 
  Dr. 
  H. 
  E. 
  Anthony 
  and 
  George 
  G. 
  

   Goodwin, 
  American 
  Museum 
  of 
  Natural 
  History, 
  New 
  York, 
  N. 
  Y. 
  ; 
  

   J. 
  Kenneth 
  Doutt, 
  Carnegie 
  Museum, 
  Pittsburgh, 
  Pa.; 
  Dr. 
  H. 
  C. 
  

   Oberholser, 
  Cleveland 
  Museum 
  of 
  Natural 
  History, 
  Cleveland, 
  Ohio; 
  

   Dr. 
  William 
  H. 
  Burt, 
  University 
  of 
  Michigan, 
  Museum 
  of 
  Zoology, 
  

   Ann 
  Arbor, 
  Mich., 
  and 
  to 
  the 
  latter 
  also 
  for 
  the 
  opportunity 
  to 
  

   examine 
  specimens 
  in 
  the 
  Donald 
  R. 
  Dickey 
  collection. 
  

  

  In 
  lists 
  of 
  specimens 
  examined, 
  the 
  following 
  abbreviations 
  are 
  

   employed 
  : 
  

  

  A. 
  H. 
  S., 
  Collection 
  of 
  Dr. 
  Adolph 
  H. 
  Scbnltz. 
  

  

  A. 
  M. 
  N. 
  H., 
  American 
  Musenm 
  of 
  Natural 
  History. 
  

  

  C. 
  D., 
  Collection 
  of 
  Donald 
  R. 
  Dickey. 
  

  

  C. 
  M., 
  Carnegie 
  Museum. 
  

  

  C. 
  M. 
  N. 
  H., 
  Cleveland 
  Museum 
  of 
  Natural 
  History. 
  

  

  M. 
  C. 
  Z., 
  Museum 
  of 
  Comparative 
  Zoology. 
  

  

  U. 
  M. 
  M. 
  Z., 
  University 
  of 
  Michigan, 
  Museum 
  of 
  Zoology. 
  

  

  U. 
  S. 
  N. 
  M., 
  United 
  States 
  National 
  Museum. 
  

  

  All 
  measurements 
  are 
  in 
  millimeters. 
  The 
  external 
  measurements 
  

   were 
  taken 
  in 
  the 
  flesh 
  by 
  the 
  collector 
  as 
  follows 
  : 
  Total 
  lengthy 
  nose 
  

   to 
  end 
  of 
  terminal 
  vertebra; 
  tail, 
  upper 
  base 
  of 
  tail 
  to 
  end 
  of 
  terminal 
  

   vertebra; 
  hind 
  foot, 
  back 
  of 
  heel 
  to 
  end 
  of 
  longest 
  nail 
  on 
  digit. 
  The 
  

   following 
  cranial 
  measurements 
  of 
  typical 
  adults, 
  unless 
  otherwise 
  

   stated, 
  were 
  taken 
  with 
  vernier 
  calipers 
  by 
  the 
  authors: 
  Greatest 
  

   length, 
  distance 
  from 
  anterior 
  tip 
  of 
  premaxillae 
  to 
  inion 
  or 
  extreme 
  

   posterior 
  median 
  point 
  of 
  brain 
  case 
  ; 
  orhital 
  width, 
  distance 
  between 
  

   outer 
  margins 
  of 
  orbits; 
  'postorbital 
  constriction, 
  least 
  width 
  at 
  con- 
  

   striction 
  behind 
  orbits; 
  width 
  of 
  hrain 
  case, 
  greatest 
  width 
  of 
  brain 
  

   case 
  at 
  or 
  over 
  mastoids 
  ; 
  zygomatic 
  hreadth, 
  greatest 
  distance 
  between 
  

   outside 
  surfaces 
  of 
  zygomata 
  ; 
  inaxiUary 
  tooth 
  row, 
  distance 
  from 
  front 
  

   of 
  canine 
  to 
  back 
  of 
  posterior 
  upper 
  molar 
  at 
  alveolar 
  borders. 
  

  

  The 
  following 
  treatment 
  is 
  based 
  on 
  a 
  review 
  of 
  the 
  scattered 
  lit- 
  

   erature 
  and 
  an 
  examination 
  of 
  251 
  specimens 
  representing 
  all 
  the 
  

   recognized 
  species. 
  The 
  work 
  has 
  been 
  done 
  at 
  the 
  request 
  of 
  the 
  

   Board 
  for 
  the 
  Coordination 
  of 
  Malarial 
  Studies 
  of 
  the 
  National 
  Re- 
  

  

  