﻿H. 
  G. 
  SEELET 
  ON 
  NEFSTICOSAUEUS 
  PUSILLUS. 
  

  

  359 
  

  

  bone, 
  is 
  known 
  to 
  exist 
  in 
  any 
  Crocodile. 
  In 
  Plesiosanrs, 
  however, 
  

   the 
  clavicles 
  have 
  become 
  small 
  or 
  absent, 
  and 
  blended 
  with 
  the 
  

   greatly 
  enlarged 
  interclavicle 
  in 
  those 
  species 
  in 
  which 
  they 
  have 
  

   been 
  observed 
  ; 
  so 
  that 
  in 
  this 
  respect 
  the 
  clavicular 
  region 
  in 
  

   Plesiosaurus 
  is 
  rather 
  more 
  like 
  that 
  of 
  the 
  Crocodile 
  than 
  is 
  that 
  of 
  

   Noiliosaurus. 
  The 
  resemblance, 
  however, 
  cannot 
  be 
  pressed, 
  because 
  

   in 
  Plesiosaurus 
  the 
  interclavicle 
  connects 
  the 
  scapulae 
  together, 
  and 
  

   braces 
  both 
  of 
  those 
  bones 
  to 
  the 
  coracoids. 
  But 
  we 
  are 
  justified 
  

   in 
  inferring 
  that, 
  with 
  the 
  diminution 
  of 
  the 
  anterior 
  expansion 
  of 
  the 
  

   scapula 
  in 
  Crocodiles, 
  the 
  clavicle 
  became 
  lost. 
  

  

  Fig. 
  1. 
  — 
  Restoration 
  of 
  the 
  Pectoral 
  Arch 
  of 
  Neusticosaurus 
  

   (external 
  aspect). 
  

  

  a. 
  Coracoid. 
  

   c. 
  Clavicle. 
  

  

  b. 
  Scapula. 
  

  

  d. 
  Interclavicle. 
  

  

  The 
  Pelvic 
  Arch. 
  

   The 
  pelvis 
  consists, 
  as 
  usual, 
  of 
  ilium, 
  pubis, 
  and 
  ischium. 
  In 
  

   the 
  principal 
  specimen 
  (PI. 
  XIII. 
  fig. 
  1) 
  the 
  articular 
  head 
  of 
  the 
  

   ilium 
  is 
  seen 
  in 
  situ, 
  contributing 
  to 
  form 
  the 
  upper 
  and 
  major 
  portion 
  

   of 
  the 
  tripartite 
  articulation 
  ; 
  but 
  on 
  the 
  right 
  side 
  the 
  acetabulum 
  

   is 
  broken 
  away 
  ; 
  so 
  that 
  I 
  can 
  only 
  mention 
  that 
  the 
  head 
  of 
  the 
  ilium 
  

   is 
  rhomboid, 
  4 
  mm. 
  wide, 
  and 
  5 
  mm. 
  deep. 
  The 
  pubic 
  and 
  ischiac 
  

   bones 
  meet 
  by 
  suture 
  in 
  the 
  median 
  line, 
  and 
  extend 
  over 
  4 
  or 
  5 
  

   vertebrae. 
  The 
  length 
  of 
  the 
  pelvic 
  region, 
  formed 
  by 
  these 
  two 
  

   bones 
  is 
  about 
  2 
  cm. 
  The 
  bones 
  are 
  expanded 
  and 
  thin, 
  and 
  

   closely 
  resemble 
  the 
  corresponding 
  elements 
  in 
  Plesiosaurus. 
  The 
  

   transverse 
  measurement 
  across 
  the 
  pubic 
  bones, 
  as 
  preserved, 
  is 
  

   23 
  mm. 
  ; 
  but 
  there 
  seems 
  to 
  have 
  been 
  a 
  slight 
  displacement 
  on 
  the 
  

   left 
  side, 
  by 
  which 
  the 
  antero-posterior 
  measurement 
  of 
  the 
  bone 
  

   has 
  become 
  less 
  than 
  on 
  the 
  right 
  side. 
  Each 
  bone 
  is 
  subqua- 
  

  

  2b2 
  

  

  I 
  

  

  