﻿460 
  TROF. 
  H. 
  G. 
  SEELET 
  ON 
  THECOSPONDYLUS 
  HORNERI. 
  

  

  able 
  animal 
  thus 
  indicated 
  : 
  for 
  if 
  my 
  inference 
  from 
  the 
  condition 
  

   of 
  the 
  transverse 
  process 
  is 
  correct, 
  it 
  belongs 
  to 
  a 
  very 
  different 
  

   type 
  of 
  animal 
  from 
  the 
  Dinosaurs 
  hitherto 
  known, 
  which 
  have 
  

   heavy 
  vertebra? 
  in 
  the 
  sacral 
  region. 
  The 
  only 
  English 
  genus 
  

   (Omithopsis) 
  which 
  has 
  pneumatic 
  vertebrae 
  and 
  dense 
  bony 
  tissue, 
  

   must 
  be 
  assumed, 
  from 
  the 
  allied 
  American 
  genera, 
  to 
  have 
  had 
  a 
  

   sacrum 
  of 
  very 
  different 
  character. 
  There 
  is 
  no 
  proof 
  that 
  the 
  ver- 
  

   tebrae 
  of 
  Thecospondylus 
  were 
  pneumatic 
  : 
  but 
  the 
  bones 
  were 
  

   formed 
  on 
  the 
  lightest 
  type 
  that 
  I 
  have 
  yet 
  seen, 
  and 
  indicate, 
  

   I 
  believe, 
  an 
  ordinal 
  or 
  subordinal 
  group, 
  in 
  which 
  the 
  skeleton 
  was 
  

   not 
  pneumatic, 
  but 
  as 
  dense 
  and 
  light 
  as 
  in 
  the 
  Ornithosauria, 
  and 
  

   supported 
  on 
  powerful 
  hind 
  limbs. 
  

  

  With 
  an 
  enlightened 
  liberality 
  which 
  deserves 
  our 
  thanks, 
  Dr. 
  

   Horner 
  has 
  commissioned 
  me 
  to 
  deposit 
  the 
  specimen 
  in 
  the 
  national 
  

   collection 
  at 
  South 
  Kensington, 
  that 
  it 
  may 
  be 
  the 
  better 
  available 
  

   for 
  study. 
  

  

  i:\PLANATION 
  OF 
  PLATE 
  XIX. 
  

  

  Fig. 
  1. 
  Right 
  lateral 
  aspect 
  of 
  cast 
  of 
  neural 
  cavity 
  of 
  sacrum, 
  showing: 
  — 
  the 
  

   sequence 
  of 
  vertebrae, 
  numbered 
  1 
  to 
  7 
  ; 
  the 
  bases 
  of 
  the 
  transverse 
  

   processes 
  (t) 
  on 
  the 
  3rd, 
  4th, 
  5th, 
  and 
  6th 
  vertebras, 
  and 
  the 
  large 
  

   expanded 
  articular 
  facet 
  of 
  the 
  2nd 
  transverse 
  process 
  (ta) 
  where 
  it 
  

   joined 
  the 
  ilium; 
  the 
  apertures 
  (v) 
  for 
  the 
  passage 
  of 
  sacral 
  nerves; 
  

   and 
  (/') 
  portions 
  of 
  thin 
  dense 
  bone 
  adherent 
  to 
  the 
  neural 
  region 
  of 
  the 
  

   vertebra 
  numbered 
  4, 
  5, 
  and 
  6. 
  

   2. 
  Interior 
  aspect 
  of 
  the 
  same 
  specimen, 
  showing 
  the 
  rounded 
  underside 
  of 
  

   the 
  bodies 
  of 
  the 
  vortebra, 
  their 
  attenuation 
  posteriorly, 
  the 
  sutures 
  

   (>) 
  between 
  the 
  bodies 
  of 
  the 
  vertebra', 
  the 
  positions 
  (/) 
  from 
  which 
  

   the 
  processes 
  are 
  given 
  oif 
  and 
  their 
  divergence 
  backward 
  in 
  the 
  6th 
  

   and 
  forward 
  in 
  the 
  2nd 
  ; 
  the 
  positions 
  of 
  the 
  vascular 
  foramina 
  are 
  

   indicated 
  by 
  the 
  letter 
  //. 
  

  

  Discussion. 
  

  

  The 
  President 
  agreed 
  with 
  the 
  author 
  in 
  regarding 
  the 
  specimen 
  

   as 
  indicating 
  the 
  existence 
  of 
  a 
  new 
  genus. 
  

  

  