﻿[53] 
  DEVELOPMENT 
  OF 
  THE 
  CETACEA. 
  479 
  

  

  umn, 
  and 
  outwardly 
  is 
  fixed 
  to 
  the 
  tips 
  of 
  the 
  transverse 
  processes. 
  

   Anteriorly, 
  the 
  muscle 
  is 
  strong, 
  thick, 
  and 
  very 
  fleshy 
  ; 
  but 
  half-way 
  

   along 
  the 
  tail, 
  and 
  nearly 
  throughout 
  the 
  middle 
  line, 
  it 
  becomes 
  tendi- 
  

   nous, 
  by 
  degrees 
  thinner, 
  and 
  towards 
  the 
  end 
  is 
  little 
  else 
  than 
  a 
  glis- 
  

   tening 
  aponeurotic 
  fascia 
  with 
  coarse, 
  tough 
  fibers. 
  These 
  fibers, 
  when 
  

   unraveled 
  with 
  care, 
  separate 
  into 
  broadish 
  tendons, 
  one 
  to 
  each 
  ver- 
  

   tebra, 
  which 
  posteriorly 
  commingle 
  with 
  the 
  great 
  flat-tail 
  aponeu- 
  

   rosis. 
  

  

  "The 
  second 
  or 
  deeper 
  muscular 
  lamella, 
  also 
  taper-shaped, 
  is, 
  as 
  a 
  

   whole, 
  much 
  thicker 
  and 
  fleshy, 
  but 
  not 
  quite 
  so 
  broad 
  as 
  the 
  last. 
  

   Besides 
  a 
  very 
  small 
  slip 
  anteriorly 
  derived 
  from 
  the 
  last 
  rib, 
  it 
  has 
  

   firm 
  attachments 
  along 
  the 
  under 
  surfaces 
  of 
  the 
  two 
  lumbar 
  and 
  all 
  the 
  

   caudal 
  vertebras, 
  filling 
  the 
  interspace 
  betwixt 
  the 
  vertebral 
  bodies, 
  

   the 
  sides 
  of 
  the 
  chevron 
  bones, 
  and 
  the 
  distal 
  extremities 
  of 
  the 
  trans- 
  

   verse 
  osseous 
  elements. 
  This 
  sheet, 
  like 
  the 
  former 
  superficial 
  oue, 
  is 
  

   fleshy 
  anteriorly 
  and 
  tendinous 
  inwardly 
  and 
  behind. 
  Its 
  terminal 
  

   fascia? 
  or 
  tendons 
  are 
  more 
  cord-like, 
  and 
  with 
  less 
  difficulty 
  resolvable 
  

   into 
  separate 
  elements." 
  (Op. 
  cit, 
  pp. 
  145, 
  146.) 
  

  

  Dr. 
  Murie 
  then 
  continues 
  and 
  describes 
  a 
  lateral 
  subcaudal 
  muscle, 
  

   which 
  is 
  of 
  considerable 
  interest, 
  in 
  that 
  it 
  sends 
  its 
  tendinous 
  inser- 
  

   tion 
  backward 
  to 
  the 
  vicinity 
  where 
  the 
  margin 
  of 
  the 
  great 
  lateral 
  tail 
  

   folds 
  end 
  anteriorly. 
  His 
  account 
  of 
  it 
  is 
  as 
  follows 
  : 
  " 
  Lastly, 
  if 
  con- 
  

   sidered 
  amongst 
  the 
  subcaudal 
  muscles, 
  and 
  not 
  what 
  it 
  to 
  some 
  extent 
  

   simulates, 
  a 
  continuation 
  of 
  the 
  sacrolumbalis, 
  we 
  have 
  the 
  lateral 
  

   or 
  superficial 
  outlying 
  fusiform 
  muscle 
  intermediate 
  between 
  the 
  dorsal 
  

   and 
  ventral 
  surfaces 
  of 
  the 
  tail. 
  This 
  numerically 
  fifth 
  infracaudal 
  

   muscle, 
  narrow, 
  roundish, 
  and 
  tapering, 
  has 
  origin 
  close 
  to 
  the 
  termi- 
  

   nation 
  of 
  the 
  sacrolumbalis, 
  from 
  the 
  cartilaginous 
  tip 
  of 
  the 
  trans- 
  

   verse 
  process 
  of 
  the 
  sacral 
  or 
  first 
  true 
  caudal 
  vertebra, 
  and 
  lies 
  hori- 
  

   zontally 
  along 
  the 
  next 
  eight 
  processes. 
  It 
  terminates 
  in 
  a 
  long 
  but 
  

   strong 
  tendon 
  upon 
  the 
  surface 
  of 
  the 
  subcaudal 
  muscle, 
  mingling 
  with 
  

   its 
  fascia." 
  (Op. 
  cit 
  , 
  p. 
  146.) 
  

  

  Dr. 
  Murie 
  also 
  speaks 
  of 
  an 
  anterior 
  subcaudal 
  pair, 
  which 
  are 
  marked 
  

   quadratus 
  lumborum 
  in 
  his 
  plates. 
  

  

  While 
  the 
  writer 
  would 
  not 
  wish 
  to 
  appear 
  hypercritical, 
  he 
  cannot 
  

   agree 
  with 
  Murie 
  and 
  Stannius 
  in 
  regard 
  to 
  the 
  homologies 
  of 
  the 
  hy- 
  

   poskeletal 
  muscles 
  of 
  the 
  tail. 
  It 
  is 
  of 
  course 
  obvious 
  from 
  the 
  preced- 
  

   ing 
  description 
  that 
  the 
  whole 
  of 
  the 
  infracaudal 
  muscular 
  mass 
  in 
  the 
  

   Manatee 
  cannot 
  be 
  homologized 
  with 
  the 
  psoas 
  muscles 
  of 
  human 
  anat- 
  

   omy, 
  but 
  it 
  is 
  evidently 
  impossible 
  to 
  homologize 
  the 
  anterior 
  muscular 
  

   bundles 
  of 
  the 
  deeper 
  of 
  these 
  muscles, 
  arising 
  from 
  the 
  under 
  face 
  of 
  

   the 
  two 
  lumbar 
  vertebras, 
  with 
  anything 
  else 
  than 
  the 
  psoas 
  magnus 
  of 
  

   man. 
  Obviously, 
  if 
  we 
  bear 
  in 
  mind 
  the 
  importance 
  of 
  serial 
  homolo- 
  

   gies, 
  the 
  muscular 
  slips 
  arising 
  from 
  and 
  behind 
  the 
  sacrum 
  cannot 
  be 
  

   psoas, 
  and 
  infracoccygeus 
  and 
  sacrococcygeus 
  may 
  therefore 
  be 
  good 
  

   names 
  for 
  those 
  hinder 
  portions. 
  The 
  inner 
  pair 
  of 
  muscles 
  alluded 
  to 
  

  

  