﻿Extinct 
  Giant 
  Birds 
  of 
  Argentina. 
  43 
  

  

  such 
  a 
  bold 
  innovation 
  were, 
  however, 
  given, 
  the 
  main 
  

   feature 
  upon 
  which 
  the 
  autliors 
  appear 
  to 
  have 
  relied 
  being 
  

   the 
  absence 
  of 
  a 
  pneumatic 
  foramen 
  in 
  the 
  femur. 
  

  

  Shortly 
  after 
  the 
  appearance 
  of 
  this 
  memoir 
  — 
  which 
  must 
  

   always 
  bear 
  a 
  high 
  value 
  on 
  account 
  of 
  the 
  excellence 
  of 
  its 
  

   illustrations 
  — 
  Prof. 
  Ameghino 
  published 
  another 
  paper 
  

   criticizing 
  and 
  revising 
  the 
  work 
  of 
  Seilores 
  Moreno 
  and 
  

   Mercerat. 
  The 
  results 
  of 
  his 
  investigations 
  were 
  to 
  the 
  

   effect 
  that^ 
  while 
  the 
  genus 
  Brontornis 
  (with 
  Rostrornis 
  as 
  a 
  

   synonym) 
  was 
  entitled 
  to 
  stand, 
  the 
  whole 
  of 
  the 
  other 
  

   names 
  proposed 
  were 
  merely 
  synonyms 
  of 
  the 
  original 
  Phoro- 
  

   rhacos, 
  of 
  which 
  six 
  species 
  were 
  admitted. 
  The 
  author 
  

   added, 
  however, 
  a 
  third 
  genus, 
  which 
  he 
  named 
  Opisthodac- 
  

   tyJus, 
  distinguished 
  by 
  a 
  peculiarity 
  in 
  the 
  position 
  of 
  the 
  

   facet 
  for 
  the 
  hallux 
  on 
  the 
  tarso-metatarsus. 
  It 
  may 
  be 
  added 
  

   that, 
  although 
  Senores 
  Moreno 
  and 
  Mercerat 
  considered 
  

   the 
  birds 
  described 
  in 
  their 
  memoir 
  to 
  indicate 
  no 
  less 
  than 
  

   four 
  distinct 
  families, 
  yet 
  Prof. 
  Ameghino 
  included 
  the 
  

   whole 
  of 
  the 
  three 
  genera 
  that 
  he 
  admitted 
  in 
  the 
  single 
  family 
  

   Phororhacidie, 
  which 
  was 
  placed 
  among 
  the 
  RatitcC. 
  Although 
  

   we 
  remember 
  the 
  lesson 
  taught 
  by 
  the 
  Moas 
  as 
  to 
  the 
  

   difficulty 
  of 
  separating 
  generically 
  well-marked 
  avian 
  forms 
  

   upon 
  the 
  evidence 
  of 
  the 
  limb-bones 
  alone, 
  yet, 
  so 
  far 
  as 
  we 
  

   can 
  judge 
  from 
  the 
  materials 
  at 
  hand. 
  Prof. 
  Ameghino 
  

   appears 
  to 
  have 
  been 
  perfectly 
  justified 
  in 
  ruthlessly 
  cutting 
  

   down 
  the 
  genera 
  of 
  his 
  confreres 
  in 
  the 
  manner 
  he 
  has 
  done. 
  

  

  Having 
  said 
  thus 
  much 
  as 
  to 
  the 
  historical 
  aspect 
  of 
  the 
  

   subject, 
  we 
  are 
  in 
  a 
  position 
  to 
  consider 
  what 
  can 
  be 
  deter- 
  

   mined 
  as 
  to 
  the 
  affinities 
  of 
  these 
  remarkable 
  birds, 
  which 
  

   appear 
  to 
  have 
  been 
  very 
  common 
  in 
  Argentina 
  during 
  the 
  

   Tertiary 
  period. 
  And 
  here 
  I 
  may 
  remind 
  my 
  readers 
  that 
  

   giant 
  flightless 
  birds 
  occur 
  in 
  the 
  Lower 
  Eocenes 
  of 
  Europe 
  

   {Gastornis 
  and 
  Dasornis) 
  and 
  of 
  North 
  America 
  [Diatryma) 
  ; 
  

   but 
  that 
  at 
  ])resent 
  none 
  are 
  known 
  between 
  that 
  period 
  and 
  

   the 
  Pliocene, 
  unless, 
  indeed, 
  these 
  Argentine 
  forms 
  belong 
  

   to 
  some 
  portion 
  of 
  the 
  intervening 
  gap. 
  

  

  As 
  regards 
  dimensions, 
  it 
  appears 
  that 
  these 
  Argentine 
  

   birds 
  not 
  only 
  rivalled 
  but 
  in 
  some 
  cases 
  actually 
  excelled 
  

  

  