﻿352 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  08 
  

  

  color 
  phases 
  in 
  any 
  one 
  series 
  are 
  strictly 
  comparable 
  with 
  such 
  

   differences 
  in 
  any 
  other 
  scries. 
  Descriptions 
  of 
  coloration 
  of 
  the 
  

   races 
  are 
  based 
  on 
  the 
  superficial 
  aspects 
  of 
  individuals. 
  The 
  terminal 
  

   halves 
  of 
  the 
  hairs, 
  usually 
  consisting 
  of 
  one, 
  sometimes 
  two, 
  color 
  

   bands, 
  are 
  described 
  as 
  determining 
  the 
  color 
  of 
  the 
  individual 
  or 
  

   population. 
  The 
  color 
  of 
  the 
  basal 
  halves 
  of 
  the 
  hairs, 
  which 
  nor- 
  

   mally 
  grade 
  into 
  the 
  color 
  of 
  the 
  terminal 
  or 
  subterminal 
  portions, 
  

   is 
  so 
  variable 
  in 
  any 
  one 
  individual 
  as 
  well 
  as 
  series 
  that 
  it 
  has 
  been 
  

   completely 
  discounted 
  for 
  diagnostic 
  and 
  even 
  descriptive 
  purposes. 
  

   Group 
  assemblages 
  known 
  as 
  bands 
  or 
  clans 
  have 
  each 
  some 
  distinctive 
  

   character 
  which 
  sets 
  them 
  off 
  from 
  other 
  populations. 
  In 
  the 
  absence 
  

   of 
  samples 
  of 
  intergrading 
  populations, 
  it 
  is 
  difficult 
  to 
  assess 
  the 
  

   characters 
  which 
  unite 
  clans 
  into 
  geographic 
  races. 
  

  

  External 
  measurements 
  and 
  cranial 
  characters 
  reveal 
  nothing 
  to 
  aid 
  

   in 
  distinguishing 
  the 
  races. 
  Here 
  factors 
  of 
  age 
  and 
  sex 
  obscure 
  

   whatever 
  diagnostic 
  differences 
  may 
  exist. 
  Reduction 
  of 
  the 
  mass 
  

   of 
  available 
  material 
  into 
  comparable 
  individuals 
  yields 
  too 
  few 
  

   specimens 
  for 
  satisfactory 
  analyses 
  of 
  cranial 
  characters. 
  What 
  does 
  

   appear 
  is 
  that 
  differences 
  in 
  size 
  and 
  cranial 
  parts 
  are 
  entirely 
  indi- 
  

   vidual. 
  

  

  Present 
  material 
  reveals 
  no 
  indication 
  of 
  geographic 
  gradients 
  or 
  

   clines, 
  or 
  any 
  close 
  or 
  consistent 
  correlation 
  between 
  coloration 
  of 
  

   the 
  various 
  populations 
  and 
  their 
  respective 
  habitats. 
  Often 
  repre- 
  

   sentatives 
  of 
  the 
  same 
  species 
  occupying 
  opposing 
  banks 
  of 
  a 
  river 
  

   where 
  ecological 
  conditions 
  are 
  identical 
  may 
  prove 
  to 
  be 
  subspecif- 
  

   ically 
  distinct. 
  There 
  does 
  appear 
  to 
  be 
  some 
  seasonal 
  differences 
  

   in 
  color. 
  Micos 
  tend 
  to 
  be 
  paler 
  during 
  the 
  dry 
  season 
  than 
  in 
  the 
  

   rainy 
  season. 
  Generally, 
  however, 
  the 
  paler 
  color 
  is 
  associated 
  with 
  

   old 
  pelage 
  and 
  the 
  darker, 
  or 
  warmer, 
  color 
  with 
  new 
  pelage. 
  It 
  can- 
  

   not 
  be 
  determined 
  now 
  what 
  part, 
  if 
  any, 
  of 
  these 
  differences 
  in 
  color 
  

   may 
  be 
  related 
  to 
  external 
  factors 
  and 
  what 
  part 
  to 
  the 
  simple 
  coin- 
  

   cidence 
  of 
  the 
  cycle 
  of 
  pelage 
  change 
  with 
  seasonal 
  changes. 
  In 
  any 
  

   attempt 
  to 
  determine 
  geographic 
  gradients, 
  it 
  must 
  be 
  borne 
  in 
  mind 
  

   that 
  members 
  of 
  the 
  genus 
  Cebus 
  are 
  among 
  the 
  most 
  mobile 
  of 
  

   American 
  simians. 
  Their 
  wanderings 
  and 
  migrations 
  cover 
  more 
  

   territory 
  and 
  diversities 
  of 
  ecological 
  situations 
  than 
  is 
  commonly 
  

   supposed. 
  

  

  Sexual 
  dimorphism. 
  — 
  There 
  are 
  obvious 
  cranial 
  differences 
  between 
  

   sexes. 
  The 
  skull 
  of 
  the 
  adult 
  male 
  is 
  larger 
  and 
  more 
  heavily 
  built 
  

   throughout. 
  Temporal 
  crests, 
  weakly 
  developed 
  in 
  the 
  species, 
  are 
  

   slightly 
  better 
  defined 
  in 
  males 
  than 
  in 
  females; 
  the 
  frontal 
  region 
  

   of 
  adult 
  females 
  shows 
  the 
  same 
  slight 
  vaulting 
  noted 
  in 
  subadult 
  

   males; 
  orbital 
  rings 
  of 
  females 
  never 
  attain 
  the 
  thickness 
  of 
  those 
  of 
  

   males; 
  canines 
  and 
  lower 
  first 
  premolars 
  of 
  males 
  much 
  more 
  de- 
  

   veloped. 
  In 
  males 
  the 
  upper 
  canine 
  projects 
  more 
  than 
  12 
  mm. 
  

  

  