﻿[7J 
  DEVELOPMENT 
  OP 
  THE 
  CETACEA. 
  400 
  

  

  the 
  hind-limbs 
  of 
  pinnipeds 
  which 
  gives 
  them 
  an 
  apparently 
  longer 
  

   trunk, 
  a 
  relatively 
  wider 
  interval 
  between 
  .the 
  tore 
  and 
  hind 
  pairs 
  of 
  

   limbs. 
  The 
  backward 
  inclination 
  of 
  the 
  proximal 
  ends 
  of 
  the 
  hind 
  limbs 
  

   and 
  their 
  inclusion, 
  together 
  with 
  the 
  anterior 
  part 
  of 
  the 
  tail 
  within 
  or 
  

   below 
  the 
  integumentary 
  organs, 
  also 
  favors 
  the 
  development 
  of 
  the 
  

   fish 
  like 
  or 
  fusiform 
  aspect 
  of 
  the 
  backwardly 
  tapering 
  thorax 
  and 
  abdo- 
  

   men, 
  which 
  will 
  be 
  intensified 
  just 
  in 
  proportion 
  as 
  this 
  process 
  is 
  

   carried 
  to 
  an 
  extreme, 
  as 
  it 
  seemingly 
  has 
  been 
  in 
  the 
  Getacea. 
  

  

  To 
  generalize 
  from 
  what 
  the 
  foregoing 
  data 
  tend 
  to 
  show, 
  it 
  may 
  be 
  

   said 
  that, 
  iu 
  normal 
  Camivora 
  there 
  has 
  been 
  no 
  tendency 
  to 
  include 
  

   the 
  femoral 
  and 
  crural 
  parts 
  of 
  the 
  hind 
  limbs 
  together 
  with 
  the 
  tail, 
  

   whereas 
  there 
  has 
  been 
  such 
  a 
  tendency 
  in 
  the 
  Pinnipeds, 
  leaving 
  only 
  

   the 
  tarsal 
  and 
  pedal 
  parts 
  of 
  their 
  hind 
  limbs 
  exserted, 
  so 
  that 
  the 
  

   primary 
  horizontal 
  limb-folds 
  have 
  in 
  consequence 
  grown 
  out 
  farther 
  

   back 
  than 
  in 
  the 
  embryos 
  of 
  terrestrial 
  mammalia. 
  In 
  other 
  words, 
  the 
  

   exserted 
  terminal 
  part 
  of 
  the 
  hind 
  limb 
  of 
  the 
  pinnipeds 
  has 
  been 
  trans- 
  

   located 
  backwards 
  in 
  consequence 
  of 
  the 
  process 
  just 
  described; 
  which 
  

   involves 
  the 
  inclusion 
  of 
  the 
  proximal 
  parts 
  of 
  the 
  limb; 
  this 
  is 
  the 
  reverse 
  

   of 
  the 
  process 
  involved 
  in 
  effecting 
  the 
  translocation 
  of 
  the 
  pelvic 
  limbs 
  

   of 
  physoclist 
  fish 
  embryos, 
  in 
  which 
  the 
  shifting 
  is 
  sudden 
  and 
  occurs 
  

   in 
  another 
  way, 
  as 
  may 
  be 
  gathered 
  from 
  my 
  notice* 
  calling 
  attention 
  

   to 
  this 
  singular 
  phenomenon. 
  The 
  type 
  which 
  presents 
  the 
  morpho- 
  

   logical 
  differentiation, 
  and 
  which 
  would 
  constitute 
  it 
  a 
  connecting 
  link 
  

   bridging 
  the 
  condition 
  between 
  the 
  existing 
  position 
  of 
  the 
  representa- 
  

   tives 
  of 
  the 
  hind 
  feet, 
  viz, 
  the 
  flukes 
  in 
  whales 
  and 
  the 
  pedes 
  of 
  

   pinnipeds, 
  has 
  been 
  entirely 
  lost, 
  yet 
  there 
  are 
  existing 
  data 
  which 
  

   support 
  the 
  conclusion 
  that 
  the 
  flukes 
  represent 
  integumentary 
  limb- 
  

   folds, 
  which 
  have, 
  by 
  the 
  method 
  of 
  development 
  now 
  known 
  to 
  be 
  

   operative 
  in 
  the 
  case 
  of 
  pinnipeds, 
  been 
  led 
  to 
  grow 
  out 
  ontogenetically 
  

   far 
  remote 
  from 
  and 
  posterior 
  to 
  their 
  archaic 
  position 
  on 
  the 
  sides 
  of 
  

   the 
  tail 
  instead 
  of 
  on 
  the 
  sides 
  of 
  the 
  body. 
  The 
  flukes 
  of 
  whales, 
  

   which 
  I 
  chose 
  to 
  regard 
  as 
  the 
  representatives 
  of 
  hind-feet, 
  according 
  

   to 
  hypothesis, 
  have 
  been 
  translocated 
  backwards 
  over 
  a 
  wide 
  interval, 
  

   but 
  no 
  more 
  extensively 
  than 
  have 
  the 
  pelvic 
  limbs 
  of 
  certain 
  extreme 
  

   forms 
  of 
  physoclist 
  fishes 
  when 
  that 
  pair 
  in 
  the 
  latter 
  is 
  compared 
  in 
  

   respect 
  to 
  position 
  with 
  its 
  archaic 
  place 
  iu 
  the 
  normal 
  and 
  unspec- 
  

   jalized 
  Physostomes. 
  

  

  (4) 
  Flower 
  on 
  the 
  affinities 
  of 
  the 
  Cetaceans.— 
  AVhile 
  Flower 
  has 
  not 
  

   committed 
  himself 
  so 
  far 
  as 
  to 
  specify 
  precisely 
  the 
  form 
  from 
  which 
  

   the 
  Cetaceans 
  have 
  been 
  evolved, 
  it 
  seems 
  to 
  the 
  writer 
  that 
  the 
  dif- 
  

   ficulty 
  of 
  deriving 
  their 
  type 
  of 
  tail 
  from 
  that 
  of 
  a 
  seal 
  like 
  form 
  which 
  

   seems 
  to 
  him 
  so 
  insuperable 
  is 
  not 
  so 
  much 
  so 
  as 
  he 
  thinks, 
  but 
  I 
  will 
  

   let 
  him 
  speak 
  for 
  himself: 
  

  

  *Ou 
  the 
  translocation 
  forwards 
  of 
  tho 
  rudiments 
  of 
  the 
  pelvic 
  tins 
  in 
  the 
  embryos 
  

   pf 
  physoclist 
  fishes. 
  (Am. 
  Naturalist, 
  XIX, 
  1885; 
  pp. 
  315-317.) 
  

   S. 
  Mis. 
  70 
  28 
  

  

  