﻿448 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [22] 
  

  

  [2] 
  " 
  Iii 
  consequence 
  of 
  this 
  peculiar 
  structure 
  the 
  only 
  purpose 
  which 
  

   these 
  organs 
  can 
  subserve 
  is 
  that 
  of 
  swimming 
  - 
  . 
  On 
  land 
  progression 
  

   is 
  mainly 
  accomplished 
  by 
  a 
  wriggling 
  serpentine 
  motion 
  of 
  the 
  body, 
  

   slightly 
  assisted 
  by 
  the 
  extremities. 
  

  

  [3] 
  "In 
  the 
  Phocidce 
  the 
  tarsal 
  articulation 
  allows 
  but 
  a 
  small 
  amount 
  

   of 
  movement 
  of 
  the 
  foot, 
  which, 
  when 
  naturally 
  at 
  rest, 
  forms 
  but 
  a 
  

   slight 
  angle 
  with 
  the 
  leg. 
  

  

  # 
  * 
  * 
  # 
  * 
  # 
  * 
  

  

  [4] 
  "The 
  bones 
  of 
  the 
  pelvis 
  (of 
  the 
  Phocidce) 
  are 
  all 
  thin 
  and 
  slender." 
  

  

  \1] 
  "In 
  the 
  Otariadce 
  the 
  hind 
  limbs 
  are 
  somewhat 
  free, 
  and 
  when 
  in 
  

   a 
  natural 
  position 
  (on 
  land) 
  the 
  feet 
  are 
  turned 
  forward, 
  and 
  serve 
  to 
  

   raise 
  the 
  body 
  from 
  the 
  ground. 
  

  

  [2] 
  "They 
  also 
  (imperfectly) 
  serve 
  the 
  purpose 
  of 
  walking; 
  these 
  

   animals 
  being 
  able 
  to 
  progress 
  when 
  out 
  of 
  the 
  water 
  several 
  miles 
  an 
  

   hour, 
  and 
  to 
  run 
  for 
  a 
  short 
  distance 
  with 
  nearly 
  the 
  rapidity 
  of 
  a 
  man. 
  

  

  [3] 
  "In 
  the 
  Otariadce 
  the 
  foot 
  when 
  similarly 
  at 
  rest 
  forms 
  with 
  the 
  

   leg 
  an 
  angle 
  of 
  at 
  least 
  90°. 
  

  

  [4] 
  " 
  The 
  bones 
  of 
  the 
  pelvis 
  are 
  all 
  thick 
  and 
  stout, 
  especially 
  the 
  

   walls 
  of 
  the 
  acetabula. 
  The 
  acetabula 
  are 
  themselves 
  very 
  much 
  larger 
  

   thau 
  in 
  PhocaP 
  

  

  " 
  The 
  length 
  of 
  the 
  ischio-pubic 
  part 
  [of 
  the 
  pelvis 
  of 
  Phocidce] 
  to 
  the 
  

   length 
  of 
  the 
  ilia 
  is 
  as 
  three 
  to 
  one." 
  In 
  the 
  Otariadce 
  the 
  proportions 
  

   of 
  these 
  bones 
  is 
  nearly 
  as 
  one 
  to 
  one. 
  

  

  It 
  is 
  thus 
  rendered 
  obvious 
  that 
  these 
  two 
  families 
  are 
  divergent 
  and 
  

   quite 
  distinct. 
  The 
  effects 
  of 
  degeneracy 
  are 
  most 
  apparent 
  in 
  the 
  

   pelvic 
  girdle 
  and 
  hind 
  limbs 
  of 
  the 
  Phocidce, 
  as 
  is 
  shown 
  by 
  the 
  con- 
  

   trasts 
  given 
  by 
  Mr. 
  Allen. 
  

  

  (13) 
  Tendency 
  to 
  pronation 
  of 
  the 
  pes 
  in 
  pinnipeds. 
  — 
  Professor 
  Lucas 
  

   iu 
  an 
  elaborate 
  paper 
  on 
  the 
  osseous 
  skeleton 
  of 
  the 
  seal 
  and 
  otter,* 
  

   has 
  given 
  some 
  account 
  of 
  the 
  swimming 
  habits 
  of 
  Phoca 
  and 
  its 
  os- 
  

   teology 
  which 
  are 
  of 
  interest 
  in 
  this 
  connection. 
  He 
  calls 
  attention 
  to 
  

   some 
  of 
  the 
  facts 
  already 
  alluded 
  to, 
  and 
  in 
  addition 
  directs 
  attention 
  

   to 
  the 
  strongly 
  marked 
  pronation 
  of 
  the 
  leg 
  and 
  foot, 
  the 
  dorsum 
  of 
  the 
  

   latter 
  being 
  directed 
  outwards 
  and 
  the 
  plantar 
  surface 
  inwards. 
  

  

  This 
  pronation 
  of 
  the 
  foot 
  was 
  probably 
  carried 
  still 
  farther 
  in 
  the 
  

   Protocetacean 
  type, 
  which 
  gave 
  rise 
  to 
  the 
  existing 
  forms. 
  In 
  them 
  the 
  

   foot 
  was 
  probably 
  directed 
  backward 
  and 
  so 
  greatly 
  pronated 
  as 
  to 
  

   bring 
  the 
  hallux 
  or 
  longest 
  digit 
  to 
  the 
  outer 
  or 
  external 
  margin 
  of 
  the 
  

   extremity 
  of 
  the 
  limb. 
  The 
  plantar 
  surface 
  would 
  then 
  be 
  brought 
  

   into 
  its 
  original 
  ventral 
  position, 
  while 
  the 
  dorsal 
  side 
  would 
  bo 
  supe- 
  

   rior, 
  the 
  reverse 
  of 
  which 
  would 
  have 
  been 
  the 
  case 
  had 
  the 
  limb 
  been 
  

   simply 
  swung 
  backwards 
  parallel 
  with 
  the 
  tail 
  without 
  pronation 
  or 
  

   semi-rotation 
  upon 
  its 
  own 
  axis. 
  But 
  the 
  hallux, 
  which 
  was 
  probably 
  

  

  *Die 
  Robbo 
  and 
  die 
  Otter 
  in 
  ilirem 
  Knoeken 
  and 
  Muskcl-skclct, 
  eine 
  aiuif 
  omisch- 
  

   zoologische 
  Studie. 
  Abb. 
  I. 
  Senokenbergisckcn 
  naturibrscheudeu 
  Gesollschaft, 
  VIII, 
  

   1872, 
  pp. 
  277-378, 
  pi. 
  14. 
  

  

  