﻿394 
  

  

  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  

  

  VOL. 
  08 
  

  

  ALOUATTA 
  SENICULUS 
  SENICULUS 
  

  

  Plate 
  17, 
  a-c; 
  Figure 
  55 
  

  

  Description.- 
  — 
  Hj'-oid 
  (os 
  basihyale) 
  of 
  adult 
  male 
  is 
  a 
  large 
  thin- 
  

   walled 
  subglobular 
  capsule. 
  Main 
  chamber 
  of 
  hyoid, 
  the 
  bulla, 
  opens 
  

   behind; 
  width 
  of 
  opening 
  about 
  one-half 
  or 
  less 
  greatest 
  length 
  of 
  

   bulla; 
  lateral 
  and 
  lower 
  borders 
  of 
  opening 
  subcircular 
  in 
  outline, 
  the 
  

   rim 
  rounded 
  and, 
  usually, 
  sloping 
  inward. 
  Upper 
  border 
  of 
  opening 
  

   bounded 
  by 
  rim 
  of 
  a 
  large, 
  rounded, 
  and 
  well-inflated 
  subchamber, 
  

   the 
  tentorium. 
  Each 
  upper 
  corner, 
  or 
  side, 
  of 
  tentorium 
  marked 
  by 
  

   a 
  large 
  articular 
  depression 
  for 
  thyreohyal 
  bone. 
  Inner 
  lateral 
  surface 
  

   of 
  tentorium 
  defined 
  from 
  bulla 
  by 
  bony 
  plates. 
  Each 
  outer 
  side 
  of 
  

   opening 
  usually 
  provided 
  with 
  a 
  rudimentary 
  cornicule 
  for 
  attach- 
  

   ment 
  of 
  stylohyoid 
  ligament; 
  base 
  of 
  cornicule 
  often 
  swollen 
  or 
  in- 
  

   flated. 
  A 
  median 
  ventral 
  plate, 
  sometimes 
  only 
  a 
  line, 
  parts 
  inner 
  

   surface 
  of 
  bulla. 
  Width 
  and 
  depth 
  of 
  smallest 
  adult 
  hyoid 
  bone 
  

   examined 
  are 
  38 
  by 
  55 
  mm., 
  of 
  largest, 
  55 
  by 
  80 
  mm. 
  

  

  gamenfum 
  thyreohyoideum 
  

  

  Bulla 
  hyoidei 
  

  

  artilago 
  thyreoldei 
  

   Cartilago 
  cricoidei 
  

  

  Figure 
  55. 
  — 
  Hyobranchial 
  apparatus 
  of 
  adult 
  red 
  howler, 
  Alouatta 
  seniculus 
  seniculus 
  

   (natural 
  size): 
  A, 
  Male 
  apparatus 
  with 
  bullar 
  and 
  tentorial 
  chambers 
  of 
  hyoid 
  bone 
  (os 
  

   basihyale) 
  indicated; 
  B, 
  female 
  hyoid 
  bone. 
  Fusion 
  of 
  thyreoyhal 
  bone 
  and 
  cornu 
  (not 
  

   found 
  in 
  seniculus, 
  cf. 
  straminea 
  d^ 
  , 
  fig. 
  56) 
  form 
  the 
  "cornu 
  majus" 
  of 
  human 
  anatomy. 
  

  

  i 
  

  

  Female 
  hyoid 
  considerably 
  smaller, 
  less 
  inflated, 
  hence 
  more 
  rec- 
  

   tangular 
  in 
  outline; 
  whole 
  inner 
  siu-face, 
  of 
  bulla 
  and 
  tentorium 
  com- 
  

   bined, 
  smooth 
  and 
  without 
  partitions; 
  cornicula 
  slightly 
  more 
  project- 
  

   ing 
  than 
  in 
  male 
  but 
  hardly, 
  or 
  not 
  at 
  all, 
  swollen 
  basally; 
  rim 
  of 
  

   opening 
  plane, 
  not 
  sloping 
  inward 
  as 
  in 
  male. 
  Dimensions 
  of 
  smallest 
  

   female 
  hyoid 
  examined, 
  approximately 
  22 
  by 
  38 
  mm., 
  of 
  largest, 
  27 
  

   by 
  45 
  mm. 
  Volume 
  of 
  largest 
  female 
  hyoid 
  between 
  one-fourth 
  and 
  

   one-fifth 
  that 
  of 
  largest 
  male 
  hyoid. 
  

  

  Variation. 
  — 
  Size 
  and 
  shape 
  of 
  hyoid 
  vary 
  individually 
  and 
  with 
  

   age. 
  Dimensions 
  are 
  roughly 
  proportional 
  to 
  those 
  of 
  the 
  space 
  

  

  