﻿36 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  SktiJl. 
  — 
  Similar 
  in 
  size 
  to 
  that 
  of 
  veUerosus^ 
  but 
  frontal 
  profile 
  more 
  

   convex 
  anteriorly; 
  dentition 
  rather 
  light. 
  

  

  Measurements. 
  — 
  Type 
  : 
  Total 
  length, 
  1,150 
  mm. 
  ; 
  tail 
  vertebrae, 
  766 
  ; 
  

   hind 
  foot, 
  181. 
  Two 
  adult 
  male 
  topotypes, 
  respectively 
  : 
  Total 
  length, 
  

   1,141, 
  1,090; 
  tail 
  vertebrae, 
  744, 
  817; 
  hind 
  foot, 
  167, 
  174. 
  Three 
  adult 
  

   female 
  topotypes: 
  Total 
  length, 
  1,17^, 
  1,150, 
  1,056; 
  tail 
  vertebrae, 
  756, 
  

   766, 
  713; 
  hind 
  foot, 
  169, 
  171, 
  165. 
  

  

  Skull 
  (type 
  and 
  two 
  adult 
  male 
  topotypes, 
  respectively) 
  : 
  Greatest 
  

   length, 
  109.7, 
  105.7, 
  107.8; 
  orbital 
  width, 
  57.2, 
  53.9, 
  55.6; 
  postorbital 
  

   constriction, 
  47.8, 
  44.8, 
  45.8; 
  width 
  of 
  brain 
  case, 
  59.5, 
  56.8, 
  57.3; 
  

   zygomatic 
  width, 
  65.3, 
  61, 
  66.3; 
  maxillary 
  tooth 
  row, 
  27.3, 
  27.5, 
  28. 
  

   Three 
  adult 
  female 
  topotypes, 
  respectively: 
  Greatest 
  length, 
  104.8, 
  

   108.5, 
  104.8; 
  orbital 
  width, 
  52.8, 
  54.1, 
  53.1; 
  postorbital 
  constriction, 
  

   44.6, 
  45.8, 
  45.6; 
  width 
  of 
  brain 
  case, 
  55.1, 
  57.2, 
  57; 
  zygomatic 
  width, 
  

   58.3, 
  60.2, 
  60.3; 
  maxillary 
  tooth 
  row, 
  25.7, 
  29.8, 
  28.7. 
  

  

  Remarks. 
  — 
  The 
  spider 
  monkey 
  of 
  the 
  Yucatan 
  Peninsula 
  is 
  readily 
  

   distinguished 
  by 
  the 
  silvery 
  whitish 
  underparts. 
  Specimens 
  from 
  

   Apazote, 
  Campeche, 
  and 
  Uaxactum, 
  Guatemala, 
  are 
  referable 
  to 
  the 
  

   present 
  form, 
  but 
  in 
  slightly 
  darker 
  and 
  more 
  buffy 
  underparts 
  they 
  

   indicate 
  gradation 
  toward 
  veUerosiis. 
  One 
  topotype 
  and 
  a 
  young 
  

   without 
  definite 
  locality 
  have 
  sparse 
  white 
  hairs 
  on 
  the 
  anterior 
  part 
  

   of 
  the 
  crown 
  and 
  a 
  vestige 
  of 
  a 
  white 
  forehead 
  patch 
  partially 
  con- 
  

   cealed 
  by 
  stiff 
  black 
  hairs. 
  

  

  Specimens 
  examined. 
  — 
  Total 
  number, 
  16, 
  as 
  follows 
  : 
  Mexico 
  : 
  Cam- 
  

   peche 
  : 
  Apazote, 
  1. 
  Quintana 
  Roo 
  : 
  Puerto 
  Morelos, 
  6. 
  Guatemala 
  : 
  

   Uaxactum, 
  8 
  (U. 
  M. 
  M. 
  Z.) 
  . 
  No 
  definite 
  locality, 
  1 
  (A. 
  M. 
  N. 
  H.) 
  . 
  

  

  ATELES 
  GEOFFROYI 
  PAN 
  Schlegel 
  

  

  Guatemalan 
  Spider 
  Monkey 
  

  

  Ateles 
  pan 
  Schlegel, 
  Mus. 
  Hist. 
  Nat. 
  Pnys-Bas 
  Leiden, 
  vol. 
  7, 
  livr. 
  12 
  (Monogr. 
  

   40, 
  Simiae), 
  p. 
  180, 
  1876. 
  

  

  Type 
  locality. 
  — 
  Coban, 
  Alta 
  Vera 
  Paz, 
  Guatemala. 
  

  

  Type 
  speehnen. 
  — 
  Cotypes, 
  adult 
  male 
  and 
  two 
  adult 
  females, 
  

   Museum 
  d'Histoire 
  Naturelle 
  des 
  Pays-Bas, 
  Leiden. 
  

  

  Distribution, 
  — 
  Mountains 
  of 
  central 
  Guatemala; 
  doubtless 
  inter- 
  

   grading 
  with 
  vellerosus. 
  

  

  General 
  characters. 
  — 
  A 
  very 
  dark 
  spider 
  monkey 
  with 
  lumbar 
  region 
  

   only 
  slightly, 
  if 
  at 
  all, 
  lighter 
  than 
  shoulders 
  and 
  thus 
  lacking 
  the 
  

   contrasting 
  dorsal 
  areas 
  presented 
  by 
  vellerosus 
  and 
  other 
  Middle 
  

   American 
  races 
  ; 
  pelage 
  long 
  and 
  dense. 
  

  

  Color. 
  — 
  Face, 
  top 
  of 
  head, 
  shoulders, 
  outer 
  surfaces 
  of 
  limbs, 
  fore- 
  

   arms 
  all 
  around, 
  feet, 
  and 
  entire 
  tail 
  black 
  or 
  brownish 
  black. 
  In 
  one 
  

   specimen 
  the 
  dark 
  color 
  extends 
  nearly 
  uniformly 
  over 
  all 
  of 
  the 
  

   upperparts, 
  but 
  in 
  two 
  others 
  the 
  lower 
  part 
  of 
  the 
  back 
  is 
  suffused 
  

   with 
  cinnamon 
  partially 
  concealed 
  by 
  overlying 
  dusky 
  hairs; 
  under- 
  

  

  