﻿18 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  Type 
  specimen. 
  — 
  Unknown. 
  

  

  Distribution. 
  — 
  Western 
  Matto 
  Grosso, 
  eastern 
  Bolivia, 
  and 
  north- 
  

   eastern 
  Peru 
  to 
  the 
  Rio 
  Solimoes 
  and 
  Rio 
  Jurua, 
  Amazonas, 
  Brazil. 
  

  

  General 
  characters. 
  — 
  Entirely 
  black, 
  with 
  pelage 
  of 
  moderate 
  

   length, 
  the 
  hairs 
  on 
  midline 
  of 
  back 
  75 
  mm. 
  or 
  less, 
  and 
  on 
  upperside 
  

   of 
  tail 
  40-65 
  mm. 
  Similar 
  in 
  general 
  to 
  paniscus 
  of 
  French 
  Guiana, 
  

   but 
  face 
  black 
  instead 
  of 
  flesh 
  color; 
  pelage 
  shorter, 
  the 
  majority 
  of 
  

   hairs 
  on 
  midline 
  of 
  back 
  75 
  nxm. 
  or 
  less, 
  instead 
  of 
  75 
  to 
  150 
  ; 
  tail 
  often 
  

   more 
  than 
  twice 
  length 
  of 
  head 
  and 
  body 
  and 
  hind 
  foot 
  large 
  as 
  in 
  

   paniscus; 
  skull 
  differs 
  from 
  that 
  of 
  paniscus 
  in 
  detail. 
  Similar 
  in 
  

   color 
  to 
  A. 
  fusciceps 
  robustus 
  of 
  southeastern 
  Colombia, 
  but 
  pelage 
  

   entirely 
  black 
  without 
  the 
  short, 
  sparse 
  white 
  hairs 
  on 
  chin 
  and 
  about 
  

   the 
  mouth 
  of 
  the 
  latter 
  that 
  while 
  inconspicuous 
  appear 
  to 
  be 
  impor- 
  

   tant 
  as 
  a 
  distinguishing 
  character 
  ; 
  cranial 
  details 
  also 
  different. 
  Dif- 
  

   fers 
  from 
  A. 
  belzebuth 
  beJzebuth 
  of 
  Venezuela 
  in 
  uniform 
  black 
  in- 
  

   stead 
  of 
  contrasting 
  black 
  and 
  buffy 
  upper 
  and 
  underparts. 
  

  

  Color. 
  — 
  Epidermis 
  of 
  face 
  normally 
  black 
  and 
  entire 
  pelage 
  deep, 
  

   glossy 
  black. 
  

  

  Skull. 
  — 
  Similar 
  in 
  size 
  to 
  that 
  of 
  paniscus^ 
  but 
  brain 
  case 
  slightly 
  

   more 
  highly 
  arched 
  ; 
  rostrum 
  narrower, 
  less 
  inflated 
  at 
  base 
  and 
  slop- 
  

   ing 
  outward 
  more 
  abruptly 
  to 
  zygomata 
  ; 
  premaxillae 
  more 
  distinctly 
  

   pinched-in 
  behind 
  incisors, 
  the 
  sides 
  being 
  almost 
  parallel; 
  maxillae 
  

   more 
  truncate 
  instead 
  of 
  prolonged 
  in 
  a 
  distinct 
  ridge 
  behind 
  posterior 
  

   molars; 
  external 
  reduplications 
  of 
  pterygoids 
  less 
  extended 
  poste- 
  

   riorly, 
  the 
  posterior 
  borders 
  more 
  deeply 
  concave; 
  palate 
  narrower; 
  

   posterior 
  plane 
  of 
  last 
  molars 
  reaching 
  farther 
  posteriorly 
  into 
  ante- 
  

   rior 
  plane 
  of 
  temporal 
  fossae. 
  Differs 
  from 
  that 
  of 
  robustus 
  as 
  fol- 
  

   low^s 
  : 
  Premaxillae 
  more 
  extended 
  anteriorly 
  beyond 
  canines, 
  the 
  sides 
  

   more 
  constricted 
  and 
  more 
  nearly 
  parallel 
  at 
  diastema 
  between 
  in- 
  

   cisors 
  and 
  canines; 
  nasal 
  opening 
  more 
  elongated. 
  Compared 
  with 
  

   that 
  of 
  belzebuth 
  the 
  skull 
  is 
  very 
  similar 
  in 
  general, 
  but 
  the 
  premaxil- 
  

   lae 
  differ 
  in 
  narrowness 
  in 
  about 
  the 
  same 
  way 
  as 
  from 
  robustus. 
  

  

  Measurements. 
  — 
  An 
  adult 
  male 
  and 
  female 
  from 
  Rio 
  Comberciato, 
  

   Peru, 
  respectively 
  : 
  Total 
  length, 
  1,270, 
  1,380 
  mm.; 
  tail, 
  820, 
  880; 
  hind 
  

   foot, 
  190, 
  202. 
  Two 
  adult 
  females 
  from 
  Rio 
  Yapacani, 
  Bolivia, 
  respec- 
  

   tively 
  : 
  Total 
  length, 
  1,320, 
  1,320 
  ; 
  tail, 
  800, 
  800 
  ; 
  hind 
  foot, 
  220, 
  220. 
  

   Skull: 
  Adult 
  male 
  and 
  female 
  from 
  Rio 
  Comberciato, 
  respectively: 
  

   Greatest 
  length, 
  117.5, 
  117; 
  orbital 
  width, 
  48.9, 
  50.8; 
  width 
  of 
  brain 
  

   case, 
  64.7, 
  59.8 
  ; 
  zygomatic 
  breadth, 
  68, 
  67.8 
  ; 
  maxillary 
  tooth 
  row, 
  33, 
  

   29. 
  Two 
  adult 
  females 
  from 
  Rio 
  Yapacani, 
  respectively 
  : 
  Greatest 
  

   length, 
  121.1, 
  118.8; 
  orbital 
  width, 
  63.8, 
  59.2; 
  postorbital 
  constriction, 
  

   50.1, 
  48.7; 
  width 
  of 
  brain 
  case, 
  65.4, 
  64.7; 
  zygomatic 
  breadth, 
  71.3, 
  

   68.2; 
  maxillary 
  tooth 
  row, 
  31.4, 
  31.5. 
  

  

  Remarks. 
  — 
  The 
  large 
  black 
  spider 
  monkey 
  here 
  treated 
  as 
  A. 
  panis- 
  

   cus 
  chamek 
  appears 
  to 
  be 
  distinguished 
  as 
  the 
  most 
  completely 
  black 
  

  

  