﻿AND 
  AYES 
  OF 
  NORTH 
  AMERICA. 
  47 
  

  

  This 
  genus 
  is 
  well 
  distinguished 
  from 
  Plesiosaurus 
  by 
  the 
  peculiarity 
  of 
  the 
  scapular 
  

   arch. 
  The 
  mesosternum 
  appears 
  to 
  be 
  coossified 
  with 
  the 
  claviculi, 
  and 
  the 
  three 
  ele- 
  

   ments 
  form 
  a 
  broad 
  breast-plate. 
  If 
  the 
  claviculus 
  was 
  ever 
  united 
  with 
  the 
  scapula 
  as 
  in 
  

   Plesiosaurus, 
  no 
  evidence 
  of 
  it 
  can 
  be 
  seen 
  in 
  the 
  specimen. 
  Both 
  the 
  clavicular 
  and 
  me- 
  

   sosternal 
  elements 
  are 
  broader 
  and 
  more 
  extended 
  anteriorly. 
  

  

  The 
  American 
  genera 
  of 
  Elasmosauridae 
  may 
  be 
  compared 
  as 
  follows 
  : 
  

  

  Posterior 
  cervical 
  vertebras 
  without 
  diapophyses: 
  cervicals 
  longer, 
  compressed, 
  neck 
  

   very 
  elongate. 
  

  

  Elasmosaurus. 
  

  

  Posterior 
  cervical 
  vertebra? 
  with 
  diapophyses 
  : 
  cervicals 
  quadrate, 
  shorter, 
  depressed, 
  

   rapidly 
  diminishing 
  in 
  size, 
  hence 
  the 
  neck 
  shorter. 
  

  

  Cimoliasaurus. 
  

  

  Prof. 
  Owen 
  figures 
  and 
  describes 
  (Reptiles 
  of 
  the 
  Cretaceous, 
  Palaeontogr. 
  Soc.) 
  a 
  

   vertebra 
  which 
  very 
  closely 
  resembles 
  the 
  cervical 
  of 
  Elasmosaurus. 
  He 
  considers 
  it 
  to 
  

   be 
  the 
  cervical 
  of 
  a 
  peculiar 
  Plesiosaurus, 
  which 
  he 
  calls 
  P. 
  constrictus, 
  remarking, 
  at 
  

   the 
  same 
  time, 
  its 
  remarkably 
  inferior 
  pleurapophyses. 
  This 
  I 
  believe 
  to 
  be 
  a 
  species 
  of 
  

   Elasmosaurus 
  or 
  an 
  ally, 
  and 
  to 
  be 
  called 
  for 
  the 
  present 
  Elasmosaurus 
  constrictus. 
  

  

  ELASMOSAURUS 
  PLATYURUS, 
  Cope. 
  

  

  Leconte's 
  Notes 
  loc. 
  cit. 
  Proceed. 
  Acad 
  Nat. 
  Sci., 
  1868, 
  1. 
  c. 
  92. 
  

   Discosaurus 
  carinatus, 
  Cope. 
  Leconte's 
  Notes, 
  1. 
  c. 
  

  

  This, 
  after 
  Mosasaurus 
  the 
  most 
  elongate 
  of 
  the 
  sea 
  saurians 
  yet 
  discovered, 
  is 
  represented 
  by 
  a 
  more 
  than 
  

   usually 
  complete 
  skeleton 
  in 
  the 
  Museum 
  of 
  the 
  Academy 
  of 
  Natural 
  Sciences 
  in 
  this 
  city. 
  It 
  -was 
  found 
  by 
  Dr. 
  

   Theophilus 
  H. 
  Turner, 
  the 
  physician 
  of 
  the 
  garrison 
  at 
  Fort 
  Wallace, 
  a 
  point 
  situated 
  300 
  miles 
  westward 
  from 
  

   Leavenworth 
  on 
  the 
  Missouri 
  river, 
  and 
  some 
  distance 
  north 
  from 
  the 
  Smoky 
  Hill 
  Fork 
  of 
  the 
  Platte 
  river. 
  Portions 
  

   of 
  two 
  vertebrae 
  presented 
  by 
  him 
  to 
  Dr. 
  Leconte 
  when 
  on 
  his 
  geological 
  tour 
  in 
  the 
  interest 
  of 
  the 
  L 
  T 
  . 
  S. 
  Pacific 
  

   Railroad 
  Company, 
  were 
  brought 
  by 
  the 
  latter 
  gentleman 
  to 
  the 
  Academy, 
  and 
  indicated 
  to 
  the 
  writer 
  the 
  existence 
  

   of 
  an 
  unknown 
  Plesiosauroid 
  reptile. 
  Subsequent 
  correspondence 
  with 
  Dr. 
  Turner 
  resulted 
  in 
  his 
  employing 
  a 
  

   number 
  of 
  men, 
  who 
  engaged 
  in 
  excavations, 
  and 
  succeeded 
  in 
  obtaining 
  a 
  large 
  part 
  of 
  the 
  monster. 
  Its 
  vertebras 
  

   were 
  found 
  to 
  be 
  almost 
  continuous, 
  except 
  a 
  vacancy 
  of 
  some 
  four 
  feet 
  in 
  the 
  interior 
  dorsal 
  region. 
  They 
  formed 
  

   a 
  curved 
  line, 
  a 
  considerable 
  part 
  of 
  whose 
  convexity 
  was 
  visible 
  on 
  the 
  side 
  of 
  a 
  bluff 
  of 
  clay 
  shale 
  rock, 
  with 
  seams 
  

   and 
  crystals 
  of 
  gypsum. 
  The 
  bones 
  were 
  all 
  coated 
  with 
  a 
  thin 
  layer 
  of 
  gypsum, 
  and 
  in 
  some 
  places 
  their 
  dense 
  layer 
  

   had 
  been 
  destroyed 
  by 
  conversion 
  into 
  sulphate 
  of 
  lime. 
  

  

  The 
  scapular 
  arch 
  was 
  found 
  in 
  large 
  part 
  adhering 
  to 
  the 
  bodies 
  and 
  neural 
  spines 
  of 
  a 
  series 
  of 
  the 
  anterior 
  dor- 
  

   sal 
  vertebras, 
  and 
  was 
  detached 
  from 
  it 
  at 
  the 
  Academy. 
  The 
  pelvic 
  arch 
  had 
  been 
  slightly 
  crushed, 
  and 
  the 
  lumbo- 
  

   sacral 
  vertebrae 
  forced 
  into 
  contact 
  with 
  the 
  ischia, 
  where 
  they 
  remain. 
  A 
  broken 
  extremity 
  of 
  the 
  supposed 
  ilium 
  

   was 
  forced 
  into 
  the 
  matrix 
  which 
  supports 
  the 
  ischia. 
  Many 
  of 
  the 
  dorsal 
  and 
  caudal 
  vertebrae 
  were 
  sent, 
  and 
  remain 
  

   in 
  continuous 
  masses, 
  so 
  that 
  the 
  succession 
  is 
  readily 
  traced, 
  and 
  the 
  true 
  relations 
  of 
  the 
  extremities 
  preserved. 
  

  

  In 
  removing 
  the 
  matrix 
  from 
  beneath 
  the 
  vertebrae, 
  scales 
  and 
  teeth 
  of 
  some 
  six 
  species 
  of 
  Physoelyst 
  and 
  

   Physostomous 
  fishes 
  were 
  found, 
  including 
  an 
  Enchodus 
  and 
  a 
  Sphyraena, 
  the 
  latter 
  indicating 
  a 
  new 
  species, 
  which 
  

   I 
  have 
  called 
  S. 
  carinata. 
  These 
  animals 
  had 
  doubtless 
  been 
  the 
  food 
  of 
  the 
  Elasmosaurus. 
  

  

  