﻿AND 
  AVES 
  OF 
  NORTH 
  AMERICA. 
  91 
  

  

  number 
  of 
  the 
  metatarsals. 
  Thus 
  so 
  far 
  as 
  known, 
  according 
  to 
  Owen, 
  Hylaeosaurus 
  

   Mant. 
  had 
  three 
  closely 
  approximate 
  metatarsals. 
  In 
  Hadrosaurus 
  they 
  are 
  elongate, 
  but 
  

   their 
  number 
  is 
  unknown. 
  In 
  Iguanodon, 
  Owen 
  represents 
  a 
  fourth, 
  but 
  rudimental 
  

   metatarsal, 
  the 
  hind 
  foot 
  being 
  still 
  three-toed, 
  while 
  in 
  the 
  more 
  ancient 
  genus 
  Scelido- 
  

   saurus, 
  the 
  same 
  authority 
  gives 
  four 
  shortened 
  metatarsals, 
  of 
  which 
  the 
  smallest 
  supports 
  

   a 
  digit 
  ; 
  and 
  a 
  fifth 
  rudimental 
  metatarsus, 
  which 
  supports 
  no 
  digit. 
  In 
  Stenopelix 
  there 
  

   appear 
  to 
  be 
  five 
  digit 
  bearing 
  metatarsals 
  according 
  to 
  Von 
  Meyer. 
  

   This 
  order 
  is 
  then 
  probably 
  divisible 
  into 
  the 
  following 
  families 
  : 
  

  

  I. 
  Teeth 
  in 
  several 
  rows 
  forming 
  a 
  vertical 
  pavement 
  ; 
  metatarsals 
  1 
  three. 
  

  

  HADROSAURIDAE. 
  

  

  Embracing 
  the 
  genus 
  Hadrosaurus, 
  Leidy. 
  

  

  II. 
  Teeth 
  in 
  a 
  single 
  row, 
  cutting 
  ; 
  three 
  digit 
  bearing 
  metatarsals. 
  

  

  IGUANODONTIDAE. 
  

   Genera 
  Iguanodon 
  Buckl. 
  Hylaeosaurus 
  Mant. 
  \ 
  Palaeoscincus, 
  Leidy. 
  

  

  III. 
  Teeth 
  in 
  a 
  single 
  row, 
  cutting 
  ; 
  four 
  digit 
  bearing 
  metatarsals. 
  

  

  SCELIDOSAURIDAE. 
  

  

  Genera 
  Scelidosaurus, 
  Owen. 
  Stenopelix 
  Myr. 
  (? 
  teeth). 
  The 
  last 
  named 
  genus 
  is 
  

   known 
  from 
  a 
  single 
  skeleton, 
  in 
  which 
  according 
  to 
  Von 
  Meyer, 
  the 
  sacral 
  vertebras 
  are 
  

   all 
  distinct. 
  It 
  is 
  perhaps 
  an 
  immature 
  individual. 
  

  

  HADROSAURUS, 
  Leidy. 
  

  

  Proc. 
  xVc. 
  Nat. 
  Sci. 
  Phila., 
  1858, 
  218. 
  Cretaceous 
  Reptiles 
  N. 
  Am., 
  7G. 
  TracJwdon, 
  Leidy, 
  L. 
  C. 
  1856. 
  ? 
  Thes- 
  

   pesius, 
  Leidy 
  1. 
  c. 
  

  

  This 
  genus 
  embraces 
  at 
  least 
  two 
  species 
  which 
  are 
  among 
  the 
  most 
  gigantic 
  terrestrial 
  

   animals 
  of 
  which 
  we 
  have 
  any 
  knowledge. 
  They 
  represent 
  the 
  Iguanodon 
  of 
  the 
  old 
  

   continent, 
  whose 
  species 
  is 
  similar 
  in 
  bulk. 
  The 
  two 
  genera, 
  however, 
  differ 
  in 
  many 
  

   details. 
  The 
  teeth, 
  as 
  above 
  noted, 
  are 
  different. 
  The 
  spines 
  of 
  the 
  dorsal 
  vertebra?, 
  

   instead 
  of 
  being 
  flat 
  anteriorly, 
  are 
  smaller 
  and 
  slender 
  subcylindric. 
  

  

  Most 
  of 
  the 
  characters 
  of 
  this 
  genus 
  have 
  been 
  given 
  by 
  Leidy 
  in 
  his 
  description 
  of 
  

   H. 
  foulkii. 
  I 
  add 
  a 
  more 
  complete 
  examination 
  into 
  the 
  characters 
  of 
  the 
  scapular 
  and 
  

   pelvic 
  arches, 
  which 
  are 
  but 
  lightly 
  treated 
  of 
  in 
  the 
  " 
  Cretaceous 
  Reptiles 
  of 
  N. 
  America." 
  

  

  Scapula. 
  — 
  Here 
  may 
  be 
  introduced 
  a 
  description 
  of 
  certain 
  massive 
  bones 
  of 
  two 
  indi- 
  

   viduals 
  of 
  a 
  species 
  of 
  Dinosaur. 
  I 
  had 
  formerly 
  admitted 
  the 
  possibility 
  of 
  their 
  

   pertinence 
  to 
  the 
  pelvis 
  of 
  Hadrosaurus, 
  but 
  the 
  discovery 
  of 
  that 
  element 
  in 
  the 
  H. 
  

   foulkei, 
  indicates 
  that 
  another 
  place 
  must 
  be 
  sought 
  for 
  them. 
  

  

  