﻿THE 
  SPIDER 
  MUNKEYS 
  KELLOGG 
  AND 
  GOLDMAX 
  5 
  

  

  spei-inieiis 
  of 
  paiif.fcus 
  exiuninotl 
  by 
  Tate, 
  but 
  tlu'^^e 
  wiii^like 
  thin 
  

   plates 
  are 
  in 
  reality 
  lar<ier 
  and 
  more 
  extended 
  posteriorly 
  in 
  these 
  

   and 
  in 
  other 
  specimens 
  of 
  pan>,'<ciis 
  from 
  (he 
  Amazonian 
  refrion 
  than 
  

   usual 
  in 
  this 
  genus. 
  Other 
  characters 
  that 
  have 
  been 
  ascribed 
  by 
  

   Tate 
  to 
  paniscus 
  but 
  that 
  have 
  not 
  been 
  found 
  to 
  be 
  constant 
  are 
  the 
  

   small 
  size 
  of 
  post<ilenoid 
  jjrocesses, 
  unexpanded 
  zy^jfoniata 
  of 
  nearly 
  

   uniform 
  depth, 
  and 
  narrow 
  teeth. 
  The 
  maxillary 
  tooth 
  rows 
  in 
  the 
  

   ^^enus 
  as 
  a 
  whole 
  are 
  normally 
  straight 
  and 
  convergent 
  anteriorly, 
  

   although 
  skulls 
  with 
  parallel 
  or 
  arcuate 
  tooth 
  rows 
  are 
  less 
  frequently 
  

   observed. 
  All 
  the 
  teeth 
  in 
  the 
  maxillary 
  tooth 
  rows 
  may 
  be 
  large 
  

   or 
  small, 
  and 
  the 
  individual 
  teeth 
  vary 
  in 
  size 
  in 
  relation 
  to 
  one 
  

   another. 
  The 
  posterior 
  molars 
  appear 
  to 
  be 
  the 
  most 
  variable. 
  

   They 
  are 
  usually 
  similar 
  to 
  the 
  first 
  premolars 
  in 
  crown 
  area 
  but 
  

   may 
  be 
  either 
  larger 
  or 
  smaller. 
  Examination 
  of 
  a 
  large 
  number 
  of 
  

   spider-monkey 
  skulls 
  shows 
  that 
  the 
  cranial 
  and 
  dental 
  features 
  men- 
  

   tioned 
  are 
  subject 
  everywhere 
  to 
  about 
  the 
  same 
  wide 
  range 
  of 
  indi- 
  

   vidual 
  variation. 
  Schultz 
  (Journ. 
  Mammalogy, 
  vol. 
  7, 
  No. 
  4, 
  pp. 
  

   28G-305, 
  Nov. 
  1926) 
  has 
  discussed 
  the 
  relative 
  ranges 
  of 
  variation 
  in 
  

   skull 
  measurements 
  and 
  in 
  the 
  formation 
  of 
  the 
  forehead 
  in 
  a 
  series 
  

   of 
  Atelen 
  taken 
  in 
  the 
  immediate 
  vicinity 
  of 
  one 
  camp 
  on 
  the 
  bank 
  

   of 
  the 
  Rio 
  Yoya 
  in 
  Nicaragua. 
  

  

  Beyond 
  the 
  general 
  similarity 
  and 
  the 
  range 
  of 
  the 
  usual 
  individual 
  

   variation 
  in 
  the 
  forms 
  of 
  Atrles 
  there 
  are, 
  however, 
  a 
  few 
  cranial 
  

   features 
  that 
  seem 
  to 
  be 
  worthy 
  of 
  consideration. 
  All 
  the 
  races 
  of 
  

   Ateles 
  geoffroyi 
  agree 
  closely 
  in 
  the 
  more 
  important 
  cranial 
  details, 
  

   but 
  in 
  the 
  more 
  northern 
  subspecies 
  vellerosus 
  and 
  yueatanens-ia 
  the 
  

   brain 
  case 
  is 
  slightl}' 
  narrower 
  than 
  in 
  panamensis 
  and 
  other 
  Middle 
  

   American 
  races. 
  The 
  South 
  American 
  species 
  A. 
  paniscv-f 
  and 
  ^1. 
  

   hrlzehiith 
  have 
  a 
  longer 
  rostrum, 
  a 
  more 
  strongly 
  inclined 
  backward 
  

   facial 
  piofile, 
  and 
  moie 
  elongated 
  nasal 
  openings 
  than 
  geoffroyi. 
  

   In 
  j)anisf'Uf<, 
  which 
  api)ears 
  to 
  be 
  the 
  most 
  divergent 
  in 
  cranial 
  de- 
  

   tails, 
  the 
  pf)stei-ior 
  upi)er 
  molars 
  scarcely 
  reach 
  the 
  transverse 
  plane 
  

   of 
  the 
  anterior 
  roots 
  of 
  the 
  zygomata, 
  while 
  in 
  geoffroyi 
  they 
  nonnally 
  

   jjass 
  well 
  beyond 
  this 
  plane; 
  other 
  j)ecidiar 
  chaiaeters 
  in 
  pcmisms 
  

   are 
  the 
  broad, 
  somewhat 
  swollen 
  base 
  of 
  the 
  rostrum 
  and 
  the 
  poste- 
  

   rior 
  exten.sion 
  of 
  the 
  external 
  reduplications 
  of 
  the 
  pterygoids. 
  In 
  

   cranial 
  details, 
  as 
  well 
  as 
  in 
  geogi-a|)hic 
  position, 
  At< 
  Us 
  fii.sc/a 
  ps 
  ru- 
  

   bu.shiM 
  is 
  somewhat 
  intermediate 
  iM'tween 
  geoffroyi 
  wwd 
  jxniiftcus. 
  

  

  Specinu'ns 
  examined 
  in 
  series 
  have 
  shown 
  tliat 
  altliough 
  sjnder 
  

   monkeys 
  present 
  considerable 
  variation 
  in 
  color 
  the 
  vaiiation 
  is 
  

   within 
  limits 
  beyond 
  which 
  it 
  does 
  not 
  normally 
  pass, 
  except 
  as 
  the 
  

   usual 
  intergradation 
  that 
  may 
  be 
  expected 
  Ix-tween 
  regional 
  races 
  or 
  

   subspecies. 
  The 
  coloration, 
  length 
  of 
  ptdage, 
  and 
  othei* 
  external 
  

   features, 
  when 
  determined 
  by 
  examination 
  of 
  specimens 
  in 
  suflicient 
  

   numbers, 
  prove 
  to 
  be 
  more 
  reliable 
  indices 
  to 
  subspecific 
  relationship 
  

  

  