﻿Report 
  of 
  the 
  State 
  Geologist. 
  871 
  

  

  ciently 
  reacting 
  upon 
  the 
  skeleton, 
  could 
  have 
  been 
  none 
  other 
  than 
  

   that 
  of 
  tree-climbing, 
  after 
  the 
  fashion 
  of 
  our 
  modern 
  apes, 
  the 
  soles 
  

   of 
  the 
  feet 
  firmly 
  pressed 
  against 
  the 
  tree 
  and 
  the 
  body 
  held 
  off 
  

   at 
  arm's 
  length. 
  The 
  flattening 
  of 
  the 
  tibia 
  would 
  be 
  for 
  the 
  

   purpose 
  of 
  supplying", 
  with 
  the 
  least 
  expenditure 
  of 
  bone, 
  addi- 
  

   tional 
  surface 
  for 
  the 
  lateral 
  attachment 
  of 
  muscles 
  producing 
  

   this 
  forcible 
  inversion 
  of 
  the 
  foot. 
  

  

  An 
  inspection 
  of 
  the 
  six 
  figures 
  shows 
  that 
  the 
  surface 
  oppo- 
  

   site 
  the 
  interosseous 
  ridge, 
  the 
  internal 
  surface, 
  remains 
  practically 
  

   unmodified 
  in 
  the 
  various 
  specimens 
  and 
  that 
  the 
  approach 
  to 
  the 
  

   modern, 
  normal 
  outline 
  is 
  produced 
  by 
  the 
  pushing 
  out 
  of 
  this 
  ridge 
  

   and 
  the 
  straightening 
  of 
  the 
  posterior 
  surface. 
  This 
  is 
  especially 
  

   shown 
  in 
  fig. 
  6, 
  taken 
  from 
  a 
  supposed 
  "Mound 
  -builder" 
  tibia 
  

   which 
  gives 
  an 
  index 
  of 
  .672. 
  The 
  significance 
  of 
  this 
  is 
  that 
  

   the 
  muscles, 
  whose 
  attachment 
  we 
  shall 
  endeavor 
  to 
  locate, 
  must 
  

   have 
  been 
  external. 
  Further, 
  the 
  flattening 
  is 
  confined 
  to 
  the 
  

   upper 
  half 
  of 
  the 
  bone 
  and, 
  consequently, 
  here 
  must 
  have 
  been 
  

   the 
  main 
  attachments 
  of 
  any 
  muscles 
  which 
  could 
  produce 
  it. 
  

   Obviously, 
  muscles 
  used 
  in 
  the 
  inversion 
  of 
  the 
  soles 
  of 
  the 
  foot 
  

   must 
  have 
  their 
  tendons 
  attached 
  to 
  the 
  inner 
  margin 
  of 
  the 
  

   foot. 
  Finally, 
  in 
  order 
  to 
  account 
  for 
  the 
  anterior 
  and 
  posterior 
  

   varieties 
  of 
  flattening, 
  we 
  must 
  assume 
  that, 
  at 
  least, 
  two 
  muscles 
  

   were 
  involved, 
  one 
  upon 
  each 
  side 
  of 
  the 
  ridge, 
  when 
  it 
  would 
  be 
  

   largely 
  a 
  matter 
  of 
  accident 
  as 
  to 
  which 
  gained 
  the 
  start 
  of 
  its 
  

   fellow. 
  Extra 
  use 
  would 
  bring 
  additional 
  nutrition 
  and 
  growth 
  

   and 
  call 
  for 
  corresponding 
  increase 
  in 
  bone 
  surface. 
  Without 
  

   resorting 
  to 
  any 
  knowledge, 
  whatever, 
  of 
  the 
  arrangement 
  of 
  the 
  

   muscles 
  of 
  the 
  leg, 
  we 
  have 
  shown 
  that 
  the 
  muscles 
  used 
  in 
  the 
  

   inversion 
  of 
  the 
  sole 
  and 
  at 
  the 
  same 
  time 
  in 
  modifying 
  the 
  tibia 
  

   must 
  have 
  been 
  attached 
  (1) 
  laterally; 
  (2) 
  externally; 
  (3) 
  over 
  

   the 
  upper 
  half 
  ; 
  (4) 
  with 
  tendons 
  passing 
  to 
  the 
  inner 
  margin 
  of 
  the 
  

   foot, 
  and 
  (5) 
  there 
  must 
  have 
  been, 
  at 
  least, 
  two 
  such 
  muscles, 
  

   one 
  up 
  on 
  each 
  side 
  of 
  the 
  interosseous 
  ridge. 
  Reference 
  to 
  any 
  ch 
  art, 
  

   or 
  work 
  upon 
  anatomy, 
  shows 
  that 
  there 
  are 
  two 
  strong 
  muscles 
  

   which 
  exactly 
  meet 
  these 
  requirements, 
  namely, 
  the 
  anterior 
  and 
  

   posterior 
  tibial 
  muscles. 
  The 
  tendon 
  from 
  the 
  former 
  passes 
  down- 
  

   ward, 
  in 
  front 
  of 
  the 
  tibia, 
  and 
  is 
  attached 
  to 
  the 
  base 
  of 
  the 
  

   metatarsal 
  supporting 
  the 
  great 
  toe 
  and 
  to 
  the 
  adjacent 
  surface 
  

   of 
  the 
  internal 
  cuneiform 
  bone. 
  The 
  tendon 
  of 
  the 
  latter 
  passes 
  

  

  