﻿n. 
  

  

  Lin. 
  

  

  4 
  

  

  

  3 
  

  

  

  3 
  

  

  4 
  

  

  2 
  

  

  3 
  

  

  3 
  

  

  2.5 
  

  

  2 
  

  

  10.7 
  

  

  AND 
  AVES 
  OF 
  NORTH 
  AMERICA. 
  193 
  

  

  tremity 
  an 
  open 
  sigmoid, 
  characters 
  which 
  might 
  be 
  included 
  in 
  the 
  range 
  of 
  variation 
  of 
  the 
  M. 
  dekayi. 
  The 
  form 
  

   of 
  the 
  caudal 
  vertebrae 
  is 
  that 
  of 
  M. 
  maximus, 
  and 
  differs 
  from 
  that 
  of 
  M. 
  dekayi. 
  The 
  characters 
  by 
  which 
  the 
  os 
  

   quadratum 
  differs 
  from 
  that 
  of 
  M. 
  maximus, 
  are, 
  as 
  Prof. 
  Marsh 
  informs 
  me 
  by 
  letter, 
  the 
  great 
  development 
  of 
  the 
  

   meatal 
  knob, 
  and 
  the 
  slight 
  prominence 
  of 
  the 
  median 
  posterior 
  ridge, 
  which 
  is 
  a 
  strong 
  process 
  in 
  M. 
  maximus. 
  

   These 
  characters 
  are 
  marked, 
  but 
  their 
  value 
  may 
  not 
  be 
  as 
  yet 
  fully 
  established. 
  The 
  great 
  ala 
  is 
  plane, 
  and 
  with 
  a 
  

   deep 
  marginal 
  groove? 
  

  

  The 
  number 
  of 
  mandibular 
  teeth 
  (17) 
  distinguish 
  it 
  from 
  M. 
  giganteus. 
  Their 
  crowns 
  are 
  divided 
  into 
  the 
  two 
  

   usual 
  planes, 
  and 
  are 
  scarcely 
  facetted. 
  They 
  are 
  more 
  than 
  usually 
  curved 
  outwards 
  in 
  the 
  specimen 
  described. 
  

  

  The 
  cups 
  of 
  the 
  vertebi-as 
  are 
  nearly 
  round 
  or 
  slightly 
  depressed. 
  Measurements 
  sent 
  by 
  Prof. 
  Marsh 
  are 
  as 
  follows: 
  

  

  Median 
  dorsal, 
  length, 
  

   Diameter 
  cup, 
  transverse, 
  

  

  " 
  " 
  vertical, 
  

  

  Median 
  caudal, 
  length, 
  

   . 
  Diameter 
  cup, 
  transverse, 
  

   " 
  " 
  vertical, 
  

  

  Chevron 
  bones 
  coossifled. 
  

  

  Lower 
  marl 
  bed 
  of 
  the 
  upper 
  cretaceous 
  at 
  Hornerstown, 
  Monmouth 
  Co., 
  N. 
  J. 
  Established 
  on 
  a 
  nearly 
  perfect 
  

   cranium, 
  five 
  feet 
  in 
  length, 
  and 
  numerous 
  vertebrae. 
  Discovered 
  by 
  Jno. 
  G. 
  Miers. 
  

  

  MOSASAURUS 
  DEKAYI, 
  Bronn. 
  

  

  Letheea 
  Geognostica 
  1838; 
  e 
  Dekay 
  Mosasaurus 
  in 
  Annals 
  New 
  York 
  Lye. 
  Ill- 
  135 
  

   Tab. 
  Mosasaurus 
  major, 
  Dekay, 
  Palaeontology 
  New 
  York 
  Geolog. 
  Survey, 
  1841. 
  ? 
  Mo- 
  

   sasaurus 
  carolinensis, 
  Gibbes, 
  Smithson. 
  Contrib. 
  to 
  Knowl. 
  II, 
  tab. 
  M. 
  couperi, 
  Gibbes, 
  

   I.e. 
  Mosasaurus 
  mitchillii, 
  Leidy, 
  Proceed. 
  Acad. 
  Nat. 
  Sci., 
  Phila., 
  1856; 
  Smithson. 
  

   Contrib. 
  p. 
  118, 
  tab. 
  nee 
  Geosaurus 
  mitcJiittii, 
  Dekay 
  Liodon 
  mitchilliihnjus 
  operis. 
  

   fBaseodon 
  reveisus, 
  Leidy, 
  Cretac. 
  Reptiles, 
  p. 
  118, 
  Tab. 
  X, 
  14-15. 
  

  

  This 
  species 
  is 
  most 
  abundantly 
  found 
  in 
  the 
  upper 
  cretaceous 
  green 
  sand 
  of 
  New 
  Jersey. 
  Portions 
  of 
  many 
  in- 
  

   dividuals 
  have 
  passed 
  under 
  my 
  observation; 
  among 
  them 
  two 
  presented 
  quadrate 
  bones, 
  and 
  several 
  the 
  separated 
  

   elements 
  of 
  the 
  atlas. 
  The 
  same 
  pieces, 
  of 
  several 
  other 
  species, 
  are 
  fortunately 
  at 
  my 
  disposal, 
  and 
  the 
  preceding- 
  

   cuts 
  present 
  the 
  specific 
  characters 
  to 
  be 
  observed 
  in 
  them, 
  vei*y 
  clearly. 
  

  

  Of 
  a 
  specimen 
  of 
  this 
  species 
  from 
  Holmdel, 
  Monmouth 
  Co., 
  N. 
  J., 
  described 
  by 
  Leidy, 
  there 
  is 
  sufficient 
  material 
  

   to 
  determine 
  the 
  relative 
  proportions 
  of 
  many 
  parts 
  of 
  the 
  cranium. 
  The 
  muzzle 
  is 
  figured 
  in 
  his 
  Tab. 
  XIX, 
  fig. 
  6, 
  

   and 
  shows 
  the 
  distinct 
  elevation 
  of 
  the 
  premaxillary 
  bone. 
  This 
  portion 
  is 
  lost 
  in 
  the 
  M. 
  giganteus. 
  Both 
  the 
  quad- 
  

   rate 
  bones 
  and 
  the 
  teeth 
  are 
  rather 
  smaller 
  than 
  in 
  the 
  M. 
  giganteus 
  of 
  Maastricht, 
  but 
  numerous 
  isolated 
  teeth 
  

   occur, 
  which 
  are 
  identical 
  in 
  form 
  with 
  those 
  of 
  the 
  present 
  specimen, 
  which 
  indicate 
  a 
  size 
  fully 
  equal. 
  The 
  neura- 
  

   pophysial 
  pieces 
  of 
  the 
  atlases 
  of 
  the 
  two, 
  when 
  compared, 
  (see 
  Ossemens 
  Fossiles) 
  present 
  marked 
  differences. 
  

  

  A 
  few 
  lumbar 
  vertebrae 
  have 
  been 
  figured 
  by 
  Leidy. 
  In 
  my 
  private 
  collection 
  are 
  shorter 
  or 
  longer 
  series 
  from 
  

   the 
  columns 
  of 
  four 
  additional 
  individuals. 
  Three 
  are 
  from 
  the 
  long 
  lumbo-sacral 
  region; 
  one 
  consists 
  of 
  eleven 
  ver- 
  

   tebrae; 
  their 
  length 
  together 
  is 
  20 
  in. 
  10 
  lines. 
  A 
  series 
  of 
  five 
  median 
  caudals 
  measures 
  7 
  in. 
  10 
  lin. 
  

  

  In 
  the 
  Museum 
  of 
  the 
  Academy 
  Natural 
  Sciences, 
  are 
  portions 
  of 
  the 
  vertebral 
  columns 
  of 
  six 
  individuals, 
  but 
  none 
  

   of 
  them 
  include 
  dorsals, 
  and 
  they 
  differ 
  very 
  much 
  in 
  size. 
  They 
  are 
  all 
  pentagonal 
  rounded 
  at 
  the 
  extremities, 
  more 
  

   elevated 
  and 
  angular 
  than 
  in 
  M. 
  maximus. 
  The 
  caudals 
  belong 
  to 
  the 
  larger 
  series 
  and 
  have 
  well 
  developed 
  diapo- 
  

   physes 
  and 
  anchylosed 
  chevron 
  bones. 
  The 
  caudals 
  in 
  my 
  private 
  collection 
  are 
  smaller, 
  also 
  pentagonal 
  and 
  with 
  

   chevron 
  bone 
  articulated 
  to 
  slightly 
  elevated 
  bases. 
  The 
  caudal 
  vertebra? 
  on 
  which 
  Morton 
  founded 
  his 
  M. 
  occiden- 
  

  

  AMERTCA. 
  PHIU). 
  SOO. 
  — 
  VOL. 
  XIV. 
  49 
  

  

  