﻿34 
  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  phalia 
  (Sphenoclon 
  Hyperodapedon.) 
  I 
  have 
  not 
  observed 
  it 
  in 
  any 
  of 
  the 
  Crocodilia, 
  

   but 
  the 
  palatal 
  roof 
  of 
  several 
  genera 
  of 
  this 
  order 
  is 
  unknown. 
  No 
  such 
  structure 
  is 
  

   known 
  among 
  the 
  Streptostylicate 
  Peptilia. 
  

  

  This 
  order 
  appears 
  first 
  in 
  time, 
  in 
  its 
  Sauropterygian 
  and 
  Thecodontian 
  representatives 
  

   in 
  the 
  Trias, 
  and 
  in 
  the 
  genus 
  Protorosaurus 
  Meyer, 
  even 
  in 
  the 
  Kupferschiefer, 
  a 
  member 
  

   of 
  the 
  Permian. 
  At 
  the 
  same 
  time 
  it 
  is 
  the 
  only 
  one 
  of 
  the 
  characteristically 
  extinct 
  

   types, 
  which 
  remains 
  to 
  the 
  present 
  day. 
  This 
  it 
  does 
  in 
  the 
  lihynchocephalia 
  and 
  

   especially 
  the 
  Crocodilia, 
  the 
  most 
  persistent 
  reptilian 
  type. 
  It 
  must 
  also 
  be 
  observed 
  

   that 
  the 
  Trias 
  of 
  Scotland 
  has 
  yielded 
  a 
  type 
  (Leptopleurum), 
  which 
  Huxley 
  refers 
  to 
  

   the 
  Lacertilia. 
  

  

  SATJROPTEBYGIA. 
  

  

  POLYCOTYLUS, 
  Cope. 
  

  

  This 
  genus 
  is 
  established 
  on 
  a 
  series 
  of 
  vertebrae 
  with 
  portions 
  of 
  pelvic 
  arch 
  and 
  pos- 
  

   terior 
  extremity, 
  discovered 
  in 
  the 
  upper 
  Cretaceous 
  of 
  Kansas 
  by 
  W. 
  E. 
  Webb, 
  Superin- 
  

   tendent 
  of 
  the 
  land 
  office 
  in 
  Topeka, 
  Kansas. 
  The 
  point 
  at 
  which 
  the 
  remains 
  were 
  

   found 
  is 
  about 
  five 
  miles 
  west 
  of 
  Fort 
  Wallace 
  on 
  the 
  plains 
  near 
  the 
  Smoky 
  Hill 
  river, 
  

   Kansas, 
  in 
  a 
  yellow 
  Cretaceous 
  limestone. 
  

  

  The 
  animal 
  thus 
  indicated 
  is 
  of 
  interest 
  in 
  American 
  vertebrate 
  palaeontology, 
  as 
  the 
  

   first 
  true 
  Plesiosauroid 
  discovered 
  within 
  our 
  limits. 
  That 
  its 
  affinities 
  are 
  nearer 
  to 
  

   Plesiosaurus 
  than 
  to 
  Elasmosaurus 
  will 
  be 
  apparent 
  from 
  the 
  following 
  description. 
  

  

  There 
  are 
  wholes 
  or 
  portions 
  of 
  twenty-one 
  vertebras, 
  of 
  which 
  but 
  two 
  retain 
  their 
  

   neural 
  arches, 
  and 
  six 
  are 
  represented 
  by 
  neural 
  arches 
  only. 
  Four 
  centra 
  may 
  be 
  referred 
  

   to 
  the 
  caudal 
  series, 
  the 
  remainder 
  to 
  the 
  dorsal 
  ; 
  there 
  is 
  nothing 
  to 
  indicate 
  the 
  characters 
  

   of 
  the 
  cervical 
  vertebra?. 
  All 
  of 
  these 
  vertebra?, 
  except 
  the 
  distal 
  caudals, 
  are 
  remarkable 
  

   for 
  their 
  short 
  anteroposterior 
  diameter 
  and 
  deeply 
  concave 
  articular 
  faces. 
  This 
  concavity 
  

   is 
  not 
  however 
  of 
  an 
  open 
  conic 
  form, 
  as 
  in 
  Ichthyosaurus, 
  but 
  is 
  flattened 
  at 
  the 
  fundus 
  

   thus 
  exhibiting 
  a 
  small 
  slightly 
  disciform 
  area, 
  The 
  usual 
  pair 
  of 
  venous 
  foramina 
  appears 
  

   on 
  the 
  under 
  side 
  of 
  the 
  centum. 
  The 
  neural 
  arch 
  is 
  continuous 
  with 
  the 
  latter, 
  and 
  

   exhibits 
  no 
  trace 
  of 
  connecting 
  suture. 
  The 
  diapophyses 
  arise 
  from 
  the 
  neural 
  arch 
  in 
  all 
  

   the 
  dorsals 
  ; 
  they 
  are 
  compressed 
  and 
  vertical 
  in 
  section. 
  The 
  arch 
  is 
  of 
  course 
  narrow 
  

   anteroposteriorly, 
  and 
  presents 
  a 
  pair 
  of 
  moderately 
  prominent 
  zygapophyses 
  in 
  each 
  

   direction, 
  the 
  posterior 
  as 
  usual 
  articulating 
  downwards, 
  the 
  anterior 
  upwards. 
  On 
  some 
  

   of 
  the 
  vertebra? 
  they 
  become 
  closely 
  approximated. 
  The 
  neural 
  spines 
  are 
  narrow 
  antero- 
  

   posteriorly, 
  but 
  much 
  stouter 
  transversely 
  than 
  in 
  Elasmosaurus 
  ; 
  they 
  are 
  strongly 
  grooved 
  

   at 
  the 
  base, 
  both 
  anteriorly 
  and 
  posteriorly, 
  most 
  so 
  posteriorly. 
  

  

  