﻿FROM 
  THE 
  WEALDEN 
  FORMATION 
  IN 
  THE 
  ISLE 
  OF 
  WIGHT. 
  519 
  

  

  The 
  dorsal 
  surface 
  of 
  the 
  same 
  part 
  is 
  transversely 
  sinuous, 
  being 
  

   laterally 
  hollow, 
  and 
  rendered 
  centrally 
  convex 
  by 
  a 
  stout 
  ridge- 
  

   like 
  continuation 
  of 
  the 
  shaft, 
  which, 
  expanding 
  upwards, 
  largely 
  

   supports 
  the 
  sessile, 
  trigonal, 
  articular 
  caput. 
  The 
  distal 
  end 
  has 
  

   less 
  perfectly 
  preserved 
  its 
  form. 
  A 
  trochlear 
  groove, 
  wide 
  and 
  

   shallow 
  distally, 
  prolonged 
  also 
  as 
  a 
  wide 
  shallow 
  trough 
  on 
  the 
  

   dorsal 
  surface 
  of 
  the 
  shaft, 
  and 
  deep 
  and 
  notch-like 
  ventrally, 
  very 
  

   distinctly 
  mark 
  out 
  an 
  ulnar 
  and 
  a 
  radial 
  condyle. 
  The 
  latter 
  is 
  

   ventrally 
  surmounted 
  by 
  a 
  tuberosity, 
  the 
  perfect 
  form 
  of 
  which 
  is 
  

   now 
  lost. 
  The 
  short 
  and 
  slender 
  shaft 
  has 
  a 
  roughly 
  trigonal 
  cross 
  

   section 
  ; 
  it 
  is 
  most 
  convex 
  dorsally, 
  where 
  one 
  of 
  the 
  rounded 
  angles 
  

   falls, 
  and 
  less 
  so 
  laterally 
  and 
  at 
  its 
  ventral 
  surface. 
  The 
  shaft 
  

   is 
  smooth, 
  while 
  the 
  rest 
  of 
  the 
  surface 
  of 
  the 
  bone, 
  especially 
  

   towards 
  the 
  articular 
  extremities, 
  is 
  very 
  rough. 
  

  

  If, 
  disregarding 
  the 
  hint 
  derivable 
  from 
  the 
  very 
  probable 
  asso- 
  

   ciation 
  of 
  this 
  bone 
  with 
  the 
  tibia 
  just 
  described, 
  we 
  look 
  around 
  

   amongst 
  the 
  contemporary 
  Sauria 
  of 
  the 
  Wealden 
  formation 
  for 
  the 
  

   owner 
  of 
  such 
  a 
  humerus, 
  we 
  find 
  Iguanodon 
  Mantelli 
  and 
  Megalo- 
  

   saurus 
  Bucklandi 
  immediately 
  excluded, 
  because 
  their 
  humeri 
  are 
  

   well 
  known 
  and 
  very 
  different. 
  There 
  remain 
  for 
  our 
  scrutiny 
  the 
  

   Streptospondyli 
  (S. 
  major 
  and 
  S. 
  recentior), 
  Owen, 
  the 
  (Wealden) 
  

   Cetiosauri, 
  Owen, 
  Polacanthus 
  Foxii, 
  and 
  Hylceosaurus 
  of 
  Mantell. 
  

   Of 
  these, 
  Streptospondylus 
  major 
  has 
  still 
  a 
  doubtful 
  individuality. 
  

   Prof. 
  Melville, 
  if 
  I 
  mistake 
  not, 
  long 
  since 
  suggested, 
  with 
  much 
  

   probability, 
  that 
  the 
  vertebrae, 
  then 
  and 
  still 
  the 
  only 
  evidence 
  on 
  

   which 
  this 
  species 
  was 
  founded, 
  belonged 
  to 
  the 
  cervical 
  and 
  pectoral 
  

   series 
  of 
  Iguanodon 
  Mantelli 
  ; 
  and 
  although 
  this 
  may 
  not 
  be 
  con- 
  

   ceded, 
  the 
  individuality 
  of 
  S. 
  major 
  has 
  not, 
  I 
  think, 
  been 
  so 
  de- 
  

   monstrated 
  as 
  to 
  render 
  it 
  impossible 
  that 
  these 
  vertebras 
  may 
  

   actually 
  belong 
  to 
  one 
  of 
  the 
  Sauria 
  included 
  in 
  the 
  genus 
  Cetio- 
  

   saurus 
  as 
  exemplified 
  in 
  the 
  Wealden 
  fauna 
  — 
  for 
  instance 
  to 
  0. 
  brevis, 
  

   Owen, 
  Streptospondylus 
  recentior, 
  Owen, 
  Ornithopsis 
  HuTkii, 
  Seeley. 
  

   Eucamerotus, 
  mihi, 
  has, 
  as 
  I 
  have 
  pointed 
  out 
  in 
  a 
  former 
  paper, 
  

   strong 
  formal 
  resemblances, 
  as 
  regards 
  its 
  vertebrae, 
  to 
  those 
  of 
  

   Cetiosaurus 
  oxoniensis 
  ; 
  but 
  the 
  texture 
  of 
  these 
  bones 
  is 
  very 
  

   different. 
  Until 
  recently 
  only 
  vertebrae 
  had 
  been 
  found 
  ; 
  but 
  last 
  

   autumn 
  portions 
  of 
  limb-bones 
  were 
  recovered 
  by 
  the 
  Eev. 
  W. 
  Fox 
  

   and 
  by 
  myself; 
  and 
  as 
  these 
  have 
  the 
  same 
  large- 
  celled 
  texture 
  as 
  

   the 
  vertebrae, 
  it 
  is 
  presumable 
  that 
  the 
  humerus 
  is 
  similarly 
  consti- 
  

   tuted, 
  which 
  this 
  humerus 
  is 
  not. 
  With 
  these 
  Sauria, 
  and 
  with 
  the 
  

   Cetiosaurus 
  brevis, 
  Owen, 
  of 
  the 
  Wealden, 
  and 
  also 
  with 
  Pelorosaurus 
  

   no 
  comparison 
  can 
  be 
  instituted. 
  Turning 
  to 
  Hylceosaurus 
  and 
  to 
  

   Polacanthus 
  Foxii, 
  the 
  fore 
  limb 
  of 
  the 
  latter 
  was 
  missing 
  from 
  

   Mr. 
  Fox's 
  find, 
  and 
  no 
  part 
  of 
  its 
  shoulder- 
  girdle 
  has 
  been 
  recog- 
  

   nized 
  ; 
  but 
  in 
  the 
  scapula 
  of 
  the 
  former 
  we 
  observe 
  an 
  extraordinary 
  

   massiveness 
  of 
  its 
  articular 
  end, 
  and 
  the 
  large 
  characteristic 
  trans- 
  

   verse 
  crest 
  — 
  conditions 
  which 
  harmonize 
  well 
  with 
  the 
  great 
  expan- 
  

   sion 
  of 
  the 
  proximal 
  end 
  of 
  this 
  humerus. 
  This 
  obvious 
  suitability, 
  

   coupled 
  with 
  the 
  strong 
  resemblances 
  of 
  the 
  tibiae, 
  constitute 
  better 
  

   grounds 
  for 
  referring 
  the 
  humerus 
  also 
  to 
  Hylceosaurus 
  than 
  to 
  any 
  

  

  