﻿462 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [36] 
  

  

  tion 
  as 
  swimming- 
  paddles 
  or 
  oars 
  in 
  the 
  water 
  exclusively, 
  thus 
  afford- 
  

   ing 
  an 
  explanation 
  of 
  the 
  atrophy 
  of 
  the 
  bones 
  and 
  muscles 
  of 
  the 
  erus 
  

   and 
  pes. 
  That 
  the 
  inclusion 
  of 
  the 
  hind 
  limbs 
  has 
  been 
  more 
  extensive 
  

   than 
  in 
  the 
  seals 
  is 
  shown 
  by 
  the 
  fact 
  that 
  the 
  end 
  of 
  the 
  caudal 
  series 
  

   of 
  vertebrae 
  is 
  included 
  between 
  the 
  bases 
  of 
  the 
  llukes 
  or 
  pedes 
  of 
  

   cetaceans, 
  and 
  that 
  no 
  trace 
  of 
  the 
  end 
  of 
  the 
  tail 
  as 
  found 
  in 
  the 
  former 
  

   is 
  externally 
  visible, 
  unless 
  the 
  rounded 
  tip 
  of 
  the 
  early 
  embryo 
  ceta- 
  

   cean's 
  tail 
  is 
  comparable 
  to 
  that 
  part 
  of 
  the 
  seal's 
  which 
  is 
  still 
  exserted. 
  

  

  " 
  In 
  the 
  small 
  Balccnoptera 
  rostrata 
  a 
  few 
  thin 
  fragments 
  of 
  cartilage, 
  

   embedded 
  in 
  fibrous 
  tissue, 
  attached 
  to 
  the 
  side 
  of 
  the 
  pelvic 
  bone, 
  con- 
  

   stitute 
  the 
  most 
  rudimentary 
  possible 
  condition 
  of 
  a 
  hind 
  limb, 
  and 
  could 
  

   not 
  be 
  recognized 
  as 
  such 
  but 
  for 
  their 
  analogy 
  with 
  other 
  allied 
  cases. 
  

   In 
  the 
  large 
  Korqual, 
  Balcenoptera 
  musculus, 
  G7 
  feet 
  long, 
  previously 
  

   spoken 
  of, 
  I 
  was 
  fortunate 
  enough 
  in 
  1805 
  to 
  hnd 
  attached 
  by 
  fibrous 
  

   tissue 
  to 
  the 
  side 
  of 
  the 
  pelvic 
  bone 
  (which 
  was 
  10 
  iuches 
  in 
  leugth), 
  a 
  

   distinct 
  femur, 
  consisting 
  of 
  a 
  nodule 
  of 
  cartilage 
  of 
  a 
  slightly 
  com- 
  

   pressed 
  irregularly 
  oval 
  form, 
  and 
  not 
  quite 
  1A 
  inches 
  in 
  length. 
  Other 
  

   specimens 
  of 
  the 
  same 
  animal 
  dissected 
  by 
  Van 
  Beneden 
  and 
  Professor 
  

   Struthers 
  have 
  shown 
  the 
  same 
  ; 
  in 
  one 
  case 
  partial 
  ossification 
  had 
  

   taken 
  place."* 
  

  

  It 
  is 
  singular 
  that 
  no 
  traces 
  of 
  rudiments 
  of 
  these 
  proximal 
  limb-bones 
  

   are 
  to 
  be 
  seen 
  as 
  cartilaginous 
  nodules 
  in 
  the 
  region 
  of 
  the 
  pelvis 
  of 
  very 
  

   young 
  Delphinoidea, 
  but 
  I 
  find 
  no 
  evidence 
  of 
  the 
  existence 
  of 
  any 
  such 
  

   structures 
  in 
  sections 
  of 
  the 
  pelvic 
  region 
  of 
  a 
  very 
  young 
  fcetus 
  of 
  

   GJobiocephalus. 
  

  

  In 
  the 
  cases 
  of 
  the 
  adult 
  specimens 
  of 
  Balcena 
  dissected 
  by 
  Struthers 
  

   there 
  was 
  an 
  interval 
  of 
  several 
  inches 
  between 
  the 
  pelvic 
  bones, 
  which 
  

   was 
  bridged 
  by 
  an 
  interpelvic 
  ligament. 
  On 
  comparing 
  the 
  pelvis 
  of 
  a 
  

   pinniped 
  (Otaria 
  or 
  Phoca) 
  with 
  that 
  of 
  a 
  Cetacean, 
  a 
  very 
  great 
  dif- 
  

   ference 
  is 
  apparent. 
  While 
  in 
  the 
  former 
  there 
  is 
  no 
  well-developed 
  

   symphysis 
  pubis, 
  the 
  pubic 
  bones 
  are 
  not 
  widely 
  separated 
  in 
  the 
  mid- 
  

   dle 
  line 
  as 
  in 
  the 
  latter. 
  In 
  the 
  former 
  also 
  the 
  pelvis 
  is 
  posteriorly 
  

   prolonged 
  and 
  the 
  pubic 
  bones 
  together 
  form 
  an 
  acute 
  angle 
  with 
  each 
  

   other, 
  the 
  opposed 
  bones 
  forming 
  a 
  sort 
  of 
  pubic 
  carina, 
  with 
  the 
  ischia 
  

   as 
  well 
  as 
  pubes 
  drawn 
  together 
  posteriorly. 
  

  

  The 
  pelvis 
  is 
  quite 
  well 
  developed 
  in 
  the 
  walrus, 
  but 
  in 
  Phoca 
  and 
  

   Gallorhinus 
  there 
  is 
  obviously 
  a 
  tendency 
  on 
  the 
  part 
  of 
  the 
  whole 
  os 
  

   innominatum, 
  to 
  degenerate 
  and 
  become 
  weak. 
  This 
  fact 
  becomes 
  very 
  

   obvious 
  when 
  the 
  thin 
  slender 
  ischia 
  and 
  pubes 
  of 
  some 
  pinnipeds 
  are 
  

   brought 
  to 
  mind, 
  and 
  becomes 
  still 
  more 
  apparent 
  upon 
  comparing 
  the 
  

   pelvic 
  girdle 
  with 
  the 
  well-developed 
  scapula 
  of 
  the 
  same 
  skeleton, 
  

   though 
  in 
  order 
  to 
  thoroughly 
  realize 
  the 
  fact 
  that 
  the 
  pelvis 
  of 
  the 
  

   pinnipeds 
  is 
  degenerating 
  one 
  must 
  compare 
  a 
  skeleton 
  of 
  the 
  latter 
  

   with 
  the 
  skeleton 
  of 
  a 
  Fissiped 
  of 
  about 
  the 
  same 
  size. 
  The 
  very 
  great 
  

  

  * 
  On 
  Whales, 
  past 
  and 
  present, 
  and 
  their 
  probable 
  origin. 
  Nature, 
  XXVIII, 
  1S83, 
  

   p. 
  228. 
  A 
  lecture 
  by 
  W. 
  II. 
  Flower, 
  before 
  the 
  Royal 
  Institution, 
  May 
  25, 
  1883. 
  

  

  