﻿Extinct 
  Giant 
  Birds 
  of 
  Argentina. 
  45 
  

  

  base 
  of 
  a 
  tooth-like 
  process 
  formed 
  by 
  the 
  jaw 
  itself. 
  It 
  

   appears 
  to 
  vne, 
  however, 
  that 
  this 
  swelling 
  looks 
  much 
  more 
  

   like 
  a 
  true 
  dental 
  alveolus, 
  which, 
  owing 
  to 
  the 
  shedding 
  of 
  

   its 
  tooth, 
  had 
  been 
  filled 
  up 
  with 
  bone. 
  And 
  I 
  may 
  add 
  that, 
  

   as 
  the 
  skull 
  of 
  Gastornis 
  is 
  known 
  only 
  by 
  mere 
  fragments, 
  

   its 
  restoration 
  by 
  Lemoine 
  (in 
  which 
  a 
  length 
  of 
  about 
  12 
  

   inches 
  is 
  assigned 
  to 
  the 
  mandible) 
  is 
  largely 
  conjectural. 
  

  

  Prof. 
  Ameghino 
  considers 
  that 
  PhororJiacos 
  longissimus 
  was 
  

   of 
  about 
  double 
  the 
  dimensions 
  of 
  Brontornis 
  burmeisteri, 
  in 
  

   which 
  the 
  length 
  of 
  the 
  tibia 
  was 
  30^ 
  inches 
  ! 
  

  

  With 
  regard 
  to 
  the 
  limb-bones 
  of 
  these 
  birds 
  *, 
  the 
  most 
  

   characteristic 
  features 
  appear 
  to 
  be 
  that 
  the 
  femur 
  had 
  no 
  

   pneumatic 
  foramen, 
  that 
  the 
  tibia 
  had 
  a 
  bony 
  bridge 
  over 
  the 
  

   extensor 
  canal 
  at 
  its 
  distal 
  extremity, 
  and 
  that 
  its 
  anterior 
  

   intercondylar 
  gorge 
  was 
  very 
  deep, 
  with 
  the 
  condyles 
  very 
  

   prominent. 
  The 
  tarso-metatarsus 
  is 
  of 
  considerable 
  length, 
  

   and 
  very 
  wide 
  above, 
  with 
  the 
  intercotylar 
  tuberosity 
  very 
  

   tall 
  and 
  the 
  upper 
  part 
  of 
  the 
  upper 
  surface 
  deeply 
  exca- 
  

   vated. 
  In 
  the 
  latter 
  respect 
  this 
  bone 
  resembles 
  the 
  tarso- 
  

   metatarsus 
  of 
  j^pyornis 
  ; 
  but 
  in 
  that 
  genus 
  there 
  is 
  no 
  

   intercotylar 
  tuberosity 
  to 
  this 
  bone, 
  and 
  no 
  distinct 
  inter- 
  

   condylar 
  gorge 
  to 
  the 
  tibia. 
  Gastornis 
  has 
  a 
  more 
  slender 
  

   tarso-metatarsus 
  with 
  a 
  prominent 
  intercotylar 
  tuberosity, 
  

   and 
  a 
  deep 
  intercondylar 
  gorge 
  to 
  the 
  tibia. 
  It 
  was 
  at 
  first 
  

   thought 
  that 
  the 
  hallux 
  was 
  wanting, 
  but 
  subsequent 
  re- 
  

   search 
  proved 
  this 
  to 
  be 
  incorrect. 
  Unfortunately, 
  nothing 
  

   appears 
  to 
  have 
  been 
  discovered 
  of 
  the 
  sternum 
  ; 
  and 
  the 
  

   information 
  relating 
  to 
  the 
  wings 
  is 
  still 
  very 
  meagre, 
  

   although 
  these 
  appear 
  to 
  have 
  been 
  present 
  in 
  some 
  form 
  or 
  

   other. 
  

  

  That 
  birds 
  of 
  the 
  gigantic 
  dimensions 
  of 
  Phororhacos 
  and 
  

   Brontornis 
  must 
  have 
  been 
  flightless 
  is 
  self-evident 
  ; 
  and, 
  so 
  

   far 
  as 
  the 
  present 
  descriptions 
  and 
  figures 
  admit 
  of 
  forming 
  

   a 
  judgment, 
  there 
  appear 
  no 
  characters 
  by 
  which 
  they, 
  

   in 
  common 
  with 
  Gastornis 
  and 
  Dasornis, 
  can 
  be 
  satisfactorily 
  

   separated 
  from 
  the 
  Ratitee. 
  In 
  the 
  presence 
  of 
  a 
  bony 
  bridge 
  

  

  * 
  Casts 
  of 
  some 
  of 
  the 
  limb-bones 
  of 
  Brontornis 
  bave 
  recently 
  been 
  

   receiTed 
  at 
  tbe 
  British 
  Museum. 
  

  

  