﻿MAMMALS 
  OF 
  NORTHERN 
  COLOMBIA 
  — 
  HERSHKOVITZ 
  387 
  

  

  Most 
  cranial 
  differences 
  cited 
  by 
  Tate 
  (1939, 
  p. 
  216) 
  for 
  distinguish- 
  

   ing 
  A. 
  seniculus 
  from 
  A. 
  palliata 
  have 
  been 
  found 
  to 
  be 
  either 
  exces- 
  

   sively 
  variable 
  or 
  not 
  applicable 
  to 
  the 
  species 
  in 
  question. 
  Measure- 
  

   ments 
  of 
  molariform 
  teeth 
  reveal 
  no 
  significant 
  differences 
  between 
  

   the 
  two 
  species. 
  Dimensions 
  given 
  by 
  Tate 
  for 
  outer 
  width 
  of 
  incisors 
  

   (P-P), 
  16 
  mm. 
  in 
  palliata 
  and 
  17.5 
  mm, 
  in 
  seniculus, 
  compare 
  with 
  

   a 
  range 
  of 
  13.7 
  to 
  15.5 
  mm. 
  in 
  20 
  specimens 
  of 
  the 
  former 
  and 
  12.6 
  

   to 
  17,2 
  mm. 
  in 
  75 
  specimens 
  of 
  the 
  latter. 
  Opening 
  of 
  malar 
  foramen 
  

   in 
  Tate's 
  specimens 
  is 
  2.5 
  mm. 
  in 
  palliata 
  and 
  7 
  to 
  8 
  mm, 
  in 
  seniculus. 
  

   In 
  present 
  material 
  the 
  opening 
  varies 
  from 
  2.1 
  to 
  5.5 
  in 
  palliata 
  and 
  

   2.9 
  to 
  6.0 
  in 
  seniculus. 
  The 
  shape 
  of 
  the 
  postglenoid 
  process 
  is 
  in 
  

   most 
  cases, 
  especially 
  in 
  females, 
  much 
  more 
  ligulate 
  in 
  palliata 
  than 
  

   in 
  seniculus, 
  a 
  difference 
  quite 
  the 
  reverse 
  of 
  that 
  given 
  by 
  Tate. 
  

  

  Sexual 
  dimorphism. 
  — 
  The 
  fully 
  adult 
  male 
  with 
  its 
  larger, 
  more 
  

   robust 
  head 
  and 
  body, 
  its 
  thick 
  lower 
  jaw, 
  and 
  sw^'^en 
  throat 
  covered 
  

   with 
  a 
  long 
  heavy 
  beard, 
  can 
  always 
  be 
  distinguishes 
  from 
  the 
  female, 
  

   even 
  at 
  a 
  distance. 
  The 
  smallest 
  normal 
  adult 
  male 
  is 
  usually 
  larger 
  

   than 
  the 
  largest 
  normal 
  adult 
  female 
  of 
  the 
  same 
  series, 
  in 
  nearly 
  all 
  

   measurements. 
  Tail 
  length 
  is 
  the 
  most 
  notable 
  exception. 
  In 
  females 
  

   the 
  tail 
  is 
  nearly 
  always 
  relatively 
  longer 
  and, 
  frequently, 
  actually 
  longer 
  

   than 
  that 
  of 
  some 
  males 
  of 
  the 
  same 
  series. 
  Tail 
  in 
  females 
  averages 
  

   56 
  percent 
  of 
  total 
  length; 
  in 
  males 
  54 
  percent. 
  Proportionate 
  length 
  

   of 
  tails 
  of 
  juvenals 
  is 
  about 
  58 
  percent 
  in 
  both 
  sexes. 
  Notable 
  differ- 
  

   ences 
  between 
  sexes 
  in 
  size 
  and 
  structure 
  of 
  hyoid 
  bone 
  are 
  described 
  

   later. 
  The 
  sexes 
  do 
  not 
  differ 
  in 
  color 
  or 
  color 
  pattern. 
  

  

  In 
  addition 
  to 
  size, 
  the 
  usual 
  cranial 
  differences 
  between 
  sexes 
  are 
  

   apparent. 
  In 
  males 
  the 
  canines 
  are 
  longer 
  and 
  thicker, 
  temporal 
  

   crests 
  more 
  developed 
  and 
  approximated, 
  brain 
  case 
  lower, 
  heavier, 
  

   and 
  more 
  dolichocephalic, 
  bony 
  rims 
  of 
  orbits 
  heavier, 
  mandible 
  

   larger, 
  etc. 
  

  

  Descrijition. 
  — 
  Diagnostic 
  characters 
  of 
  the 
  skull 
  have 
  been 
  given, 
  

   and 
  the 
  hyoid 
  apparatus 
  of 
  seniculus 
  is 
  described 
  hereinafter 
  (p. 
  394). 
  

   Coloration 
  and 
  measurements 
  of 
  the 
  species 
  are 
  represented 
  by 
  the 
  

   following 
  descriptions 
  of 
  each 
  series 
  of 
  red 
  howlers 
  collected 
  in 
  northern 
  

   Colombia 
  by 
  the 
  author. 
  A 
  total 
  of 
  60 
  specimens 
  (32 
  males, 
  28 
  

   females) 
  are 
  described, 
  in 
  addition 
  to 
  6 
  topotypes 
  of 
  ruhicunda 
  Allen, 
  

   from 
  Bonda, 
  Santa 
  Marta, 
  collected 
  by 
  Mrs. 
  Herbert 
  H. 
  Smith. 
  All 
  

   specimens 
  listed 
  may 
  be 
  regarded 
  as 
  typical. 
  Variations 
  in 
  color 
  are 
  

   greatest 
  between 
  age 
  groups, 
  and 
  greater 
  between 
  extremes 
  of 
  any 
  

   one 
  series 
  than 
  between 
  the 
  average 
  of 
  each 
  of 
  any 
  two 
  series. 
  In 
  

   no 
  case, 
  however, 
  is 
  the 
  range 
  of 
  variation 
  in 
  color 
  great 
  in 
  any 
  one 
  

   series. 
  Variation 
  depends 
  principally 
  upon 
  color 
  of 
  hair 
  tips 
  of 
  back. 
  

   Extent 
  of 
  the 
  pale 
  or 
  dark 
  tipping 
  determines 
  whether 
  an 
  individual 
  

   is 
  described 
  as 
  being, 
  respectively, 
  in 
  light 
  or 
  dark 
  color 
  phase. 
  Color 
  

  

  799565 
  — 
  49 
  5 
  

  

  