﻿428 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES 
  [2] 
  

  

  upon 
  the 
  significance 
  of 
  this 
  or 
  that 
  peculiarity 
  of 
  the 
  external 
  or 
  in- 
  

   ternal 
  conformation 
  of 
  the 
  different 
  parts 
  of 
  these 
  creatures, 
  as 
  corn- 
  

   pared 
  with 
  similar 
  or 
  homologous 
  parts 
  in 
  normal 
  mammalia, 
  and 
  in 
  

   the 
  aquatic 
  JSirenia 
  and 
  amphibious 
  Pinnipedia, 
  it 
  is 
  hoped 
  may 
  help 
  us 
  

   to 
  better 
  understand 
  the 
  question 
  of 
  the 
  affinities 
  of 
  these 
  organisms, 
  

   and 
  perhaps 
  afford 
  us 
  a 
  slightly 
  clearer 
  insight 
  into 
  the 
  method 
  of 
  

   phylogeny, 
  as 
  its 
  obscure 
  lines 
  converging 
  backwards 
  in 
  time, 
  are 
  here 
  

   and 
  there 
  brought 
  out 
  a 
  little 
  more 
  distinctly, 
  by 
  some 
  of 
  the 
  con- 
  

   clusions 
  which 
  may 
  be 
  drawn 
  from 
  anatomical 
  and 
  ontogenetic 
  investi- 
  

   gations. 
  If 
  the 
  view 
  here 
  advocated, 
  that 
  the 
  flukes 
  are 
  probably 
  the 
  

   degenerate 
  homologues 
  of 
  hind 
  feet 
  (not 
  the 
  homologues 
  of 
  the 
  whole 
  

   hind 
  limb, 
  as 
  was 
  held 
  by 
  Gray 
  and 
  even 
  earlier 
  authors) 
  at 
  first 
  seems 
  

   improbable, 
  such 
  a 
  view 
  may, 
  I 
  venture 
  to 
  think, 
  impress 
  the 
  fair- 
  

   minded 
  student 
  as 
  being 
  a 
  little 
  nearer 
  the 
  truth 
  than 
  the 
  compara- 
  

   tively 
  modern 
  assumption 
  universally 
  sustained 
  up 
  to 
  the 
  present 
  year 
  

   by 
  the 
  most 
  eminent 
  of 
  living 
  morphologists, 
  amongst 
  whom 
  must 
  be 
  

   named 
  Huxley, 
  Flower, 
  Claus, 
  Owen, 
  and 
  Parker, 
  that 
  the 
  hind 
  limbs 
  

   of 
  Cetacea 
  have 
  been 
  totally 
  suppressed 
  or 
  atrophied 
  outwardly, 
  thus 
  

   leading 
  to 
  the 
  avowed 
  or 
  tacitly 
  admitted 
  conclusion 
  that 
  the 
  flukes, 
  like 
  

   the 
  dorsal 
  Jin, 
  are 
  appendages 
  which 
  have 
  been 
  secondarily 
  acquired 
  or 
  

   added 
  to 
  the 
  morphological 
  combination 
  presented 
  by 
  the 
  Cetacean 
  organiza- 
  

   tion, 
  and 
  are 
  not 
  to 
  be 
  considered 
  as 
  representing, 
  as 
  seems 
  to 
  me 
  far 
  

   more 
  probable, 
  the 
  last 
  degenerate 
  vestiges 
  of 
  the 
  distal 
  portions 
  of 
  

   primordially 
  functional 
  hind 
  limbs. 
  

  

  What 
  has 
  led 
  me 
  to 
  the 
  preceding 
  conclusions 
  are 
  the 
  general 
  laws 
  

   which 
  seem 
  to 
  preside 
  over 
  limb 
  development 
  within 
  the 
  limits 
  of 
  the 
  

   Vertebrata, 
  together 
  with 
  the 
  results 
  of 
  a 
  consideration 
  of 
  the 
  effects 
  of 
  

   certain 
  degenerative 
  tendencies 
  accompanied 
  by 
  functional 
  changes 
  

   and 
  adaptations 
  manifested 
  in 
  definite 
  directions, 
  as 
  seen 
  in 
  all 
  Ceta- 
  

   ceans, 
  Sirenians, 
  and 
  Pinnipedia. 
  

  

  These 
  views 
  have 
  been 
  reached 
  quite 
  independently 
  of 
  any 
  which 
  

   have 
  been 
  previously 
  expressed 
  to 
  the 
  same 
  or 
  similar 
  effect 
  by 
  other 
  

   authors, 
  and 
  it 
  was 
  not 
  until 
  I 
  had 
  fully 
  thought 
  over 
  the 
  problem, 
  

   with 
  such 
  evidence 
  as 
  was 
  then 
  in 
  my 
  possession, 
  that 
  I 
  ventured 
  to 
  

   express 
  my 
  conclusions 
  to 
  my 
  friend, 
  Professor 
  Gill, 
  who 
  at 
  once 
  agreed 
  

   with 
  me 
  in 
  the 
  main, 
  and 
  who 
  then 
  stated 
  that 
  he 
  had 
  actually 
  pub- 
  

   lished 
  an 
  opinion 
  upon 
  the 
  subject 
  in 
  a 
  lecture* 
  delivered 
  in 
  the 
  winter 
  

   of 
  1882. 
  Professor 
  Gill 
  has 
  also 
  been 
  kind 
  enough 
  to 
  write 
  down 
  for 
  me 
  

   the 
  following 
  statement 
  of 
  his 
  views 
  : 
  " 
  These 
  characteristic 
  struct- 
  

   ures 
  are 
  in 
  my 
  opinion 
  derived 
  from 
  greatly 
  hypertrophied 
  integuments 
  

   of 
  hind 
  limbs 
  analogous 
  to 
  such 
  as 
  are 
  developed, 
  for 
  instance, 
  to 
  the 
  

   hind 
  limbs 
  of 
  the 
  eared 
  seals, 
  while 
  the 
  osseous 
  elements 
  have 
  been 
  

   inversely 
  atrophied, 
  pulled 
  forward, 
  and 
  reduced 
  to 
  supports 
  for 
  mus- 
  

   cles 
  connected 
  with 
  the 
  organs 
  of 
  generation." 
  

  

  'Scientific 
  and 
  Popular 
  Views 
  of 
  Nature 
  Contrasted, 
  a 
  lecture 
  delivered 
  in 
  the 
  

   National 
  Museum, 
  March 
  11, 
  1882, 
  pp. 
  10-11. 
  Washington, 
  1882, 
  Judd 
  & 
  Detweiler. 
  

  

  