﻿CHELONIA 
  AND 
  A 
  TOOTH 
  OF 
  (?) 
  OENITHOPSIS. 
  229 
  

  

  and 
  there 
  are 
  no 
  distinct 
  nasals, 
  but 
  we 
  have 
  the 
  same 
  complete 
  roofing 
  

   of 
  the 
  temporal 
  fossae. 
  Similar 
  features 
  are 
  presented 
  by 
  the 
  skull 
  

   figured 
  in 
  the 
  ' 
  Paheontographica,' 
  vol. 
  xxv. 
  pi. 
  xvii. 
  figs. 
  11, 
  12, 
  as 
  

   Chelonides 
  (a 
  preoccupied 
  name), 
  where 
  the 
  palatines 
  are 
  in 
  con- 
  

   tact. 
  An 
  example 
  of 
  another 
  skull 
  which 
  may 
  possibly 
  belong 
  to 
  

   this 
  generalized 
  Pleurodiran 
  type 
  is 
  the 
  large 
  one 
  from 
  the 
  Port- 
  

   Ian 
  dian, 
  described 
  by 
  Sir 
  E. 
  Owen 
  in 
  the 
  ' 
  Hep. 
  Brit. 
  Assoc.' 
  

   for 
  1841, 
  p. 
  168, 
  and 
  figured 
  in 
  his 
  'History 
  of 
  British 
  Fossil 
  

   Reptiles,' 
  vol. 
  i. 
  Chelonia, 
  pi. 
  viii. 
  figs. 
  1-3, 
  as 
  Chelone 
  planicejps. 
  

   This 
  skull 
  differs 
  from 
  the 
  one 
  referred 
  to 
  Plesiochelys 
  by 
  its 
  distinct 
  

   nasals, 
  and 
  from 
  that 
  of 
  Phinochelys 
  by 
  the 
  meeting 
  of 
  the 
  prefrontals 
  

   in 
  a 
  median 
  suture, 
  as 
  well 
  as 
  by 
  the 
  deep 
  notch 
  below 
  the 
  jugal, 
  and 
  

   •the 
  separation 
  of 
  the 
  squamosal 
  from 
  the 
  parietal. 
  This 
  skull, 
  1 
  

   propose, 
  should 
  be 
  provisionally 
  known 
  by 
  the 
  generic 
  name 
  of 
  Stego- 
  

   chelys 
  until 
  it 
  can 
  be 
  identified 
  with 
  a 
  genus 
  founded 
  on 
  the 
  shell. 
  

  

  With 
  regard 
  to 
  its 
  distribution 
  in 
  time, 
  a 
  cranium 
  in 
  the 
  British 
  

   Museum 
  (JSo. 
  P. 
  27) 
  indicates 
  the 
  occurrence 
  of 
  Phinochelys 
  in 
  the 
  

   Chalk 
  Marl 
  ; 
  while 
  other 
  specimens 
  in 
  the 
  same 
  collection 
  show 
  that 
  

   it 
  also 
  extended 
  downwards 
  to 
  the 
  Gault. 
  

  

  Before 
  proceeding 
  to 
  describe 
  the 
  species 
  of 
  Phinochelys, 
  reference 
  

   may 
  be 
  made 
  to 
  fragments 
  of 
  Chelonian 
  skulls 
  characterized 
  by 
  their 
  

   pustulate 
  exterior, 
  which 
  are 
  of 
  very 
  common 
  occurrence 
  in 
  the 
  

   Cambridge 
  Greensand, 
  and 
  to 
  which 
  Prof. 
  Seeley 
  * 
  has 
  applied 
  the 
  

   name 
  Trachydermochelys, 
  but 
  without 
  attempting 
  to 
  show 
  any 
  justi- 
  

   fication 
  for 
  generically 
  distinguishing 
  them 
  from 
  Phinochelys. 
  Prima 
  

   facie 
  there 
  is, 
  indeed, 
  every 
  probability 
  that 
  these 
  specimens 
  do 
  belong 
  

   to 
  that 
  genus, 
  as 
  being 
  the 
  commonest 
  Chelonian 
  in 
  the 
  beds 
  in 
  

   question, 
  and 
  apparently 
  the 
  only 
  one 
  not 
  referable 
  to 
  the 
  Chelonidse. 
  

   Specimens 
  in 
  Mr. 
  Jesson's 
  collection 
  indicate 
  that 
  the 
  carapace 
  to 
  

   which 
  these 
  fragments 
  belonged 
  had 
  an 
  expanded 
  and 
  everted 
  border, 
  

   as 
  in 
  many 
  existing 
  Pleurodira 
  ; 
  while 
  the 
  pustulation 
  of 
  the 
  exterior 
  

   is 
  only 
  an 
  exaggeration 
  of 
  a 
  feature 
  found 
  in 
  the 
  living 
  Pleurodiran 
  

   genus 
  Qhelodina. 
  I 
  only 
  put 
  forward 
  this 
  view 
  as 
  a 
  suggestion 
  ; 
  but 
  

   I 
  may 
  add 
  that 
  some 
  further 
  evidence 
  pointing 
  to 
  the 
  Pleurodiran 
  

   affinity 
  of 
  Phinochelys 
  is 
  afforded 
  by 
  a 
  small 
  cervical 
  vertebra 
  from 
  

   the 
  Cambridge 
  Greensand, 
  sent 
  me 
  by 
  Mr. 
  Jesson, 
  which 
  appears 
  to 
  

   have 
  distinct 
  transverse 
  processes, 
  like 
  those 
  of 
  existing 
  Pleurodirans. 
  

  

  It 
  is 
  possible 
  that 
  some 
  of 
  the 
  undermentioned 
  forms 
  may 
  really 
  

   differ 
  sufficiently 
  from 
  the 
  type 
  to 
  constitute 
  a 
  distinct 
  genus 
  ; 
  but, 
  

   for 
  the 
  present 
  at 
  least, 
  I 
  have 
  retained 
  the 
  whole 
  of 
  them 
  in 
  

   Mhinochelys. 
  

  

  Coming 
  now 
  to 
  the 
  consideration 
  of 
  species, 
  Prof. 
  Seeley, 
  on 
  

   pp. 
  xviii 
  & 
  xix 
  of 
  the 
  work 
  cited, 
  applies 
  no 
  less 
  than 
  fifteen 
  specific 
  

   names 
  (in 
  addition 
  to 
  the 
  type 
  species) 
  to 
  remains 
  of 
  this 
  genus 
  ; 
  but 
  

   since 
  none 
  of 
  them 
  have 
  been 
  defined, 
  they 
  can 
  only 
  be 
  regarded 
  as 
  

   MS. 
  names. 
  I 
  proceed, 
  therefore, 
  to 
  define 
  such 
  species 
  as 
  I 
  can 
  

   determine 
  from 
  the 
  specimens 
  in 
  Mr. 
  Jesson's 
  collection 
  and 
  in 
  that 
  

   of 
  the 
  British 
  Museum. 
  

  

  * 
  Op, 
  cit. 
  p. 
  33. 
  

  

  