﻿AND 
  AVES 
  OF 
  NORTH 
  AMERICA. 
  229 
  

  

  to 
  a 
  transverse 
  section 
  of 
  the 
  opening, 
  as 
  in 
  some 
  species 
  of 
  Python. 
  The 
  floor 
  of 
  the 
  neural 
  canal 
  is 
  somewhat 
  be- 
  

   low 
  the 
  plane 
  of 
  the 
  anterior 
  zygapophyses. 
  The 
  zygosphen 
  is 
  much 
  elevated, 
  and 
  its 
  summit 
  concave. 
  It 
  is 
  nar- 
  

   rower 
  than 
  the 
  articular 
  cup, 
  a 
  feature 
  which 
  appears 
  to 
  be 
  peculiar 
  to 
  fossil 
  serpents. 
  Its 
  anterior 
  surface 
  is 
  

   deeply 
  excavated, 
  and 
  the 
  lateral 
  margins 
  extend 
  from 
  the 
  base 
  downwards 
  and 
  outwards 
  to 
  the 
  superior 
  edge 
  of 
  the 
  

   cup, 
  thus 
  continuing 
  the 
  sides 
  of 
  the 
  neural 
  canal 
  forward. 
  The 
  zygantrum 
  is 
  comparitively 
  shallow, 
  and 
  has 
  its 
  great- 
  

   est 
  depth 
  on 
  the 
  medial 
  line. 
  Its 
  base 
  extends 
  downwards 
  and 
  backwards 
  until 
  directly 
  over 
  the 
  superior 
  margin 
  of 
  

   the 
  ball, 
  protecting 
  also 
  from 
  above 
  the 
  neural 
  canal 
  posteriorly. 
  The 
  neural 
  spine 
  is 
  much 
  compressed, 
  triangular 
  in 
  

   outline 
  at 
  its 
  base, 
  and 
  does 
  not 
  extend 
  to 
  the 
  anterior 
  margin 
  of 
  the 
  zygosphen. 
  The 
  base 
  of 
  the 
  neural 
  arch 
  is 
  

   strengthened 
  by 
  a 
  thick 
  rounded 
  ridge, 
  which 
  unites 
  the 
  zygapophyses 
  on 
  each 
  side. 
  It 
  begins 
  below 
  the 
  plane 
  of 
  the 
  

   anterior 
  zygapophysis, 
  and 
  ascending 
  slightly, 
  joins 
  the 
  posterior 
  zygapophysis 
  above 
  the 
  articular 
  face. 
  Remnants 
  

   of 
  two, 
  hypapophyses 
  connected 
  by 
  a 
  prominent 
  ridge 
  exist, 
  and 
  show 
  that 
  the 
  anterior 
  process 
  was 
  much 
  the 
  smaller 
  

   and 
  its 
  base 
  somewhat 
  separated 
  from 
  the 
  margin 
  of 
  the 
  cup. 
  

  

  The 
  principal 
  dimensions 
  of 
  this 
  vertebra, 
  which 
  is 
  apparently 
  an 
  anterior 
  dorsal, 
  are 
  as 
  follows: 
  — 
  

  

  Linen. 
  

  

  Length 
  of 
  centrum 
  from 
  edge 
  of 
  cup 
  to 
  convexity 
  of 
  ball, 
  14.25 
  

  

  Transverse 
  diameter 
  of 
  cup, 
  9.10 
  

  

  Vertical 
  diameter 
  of 
  cup, 
  7.5 
  

  

  Distance 
  from 
  top 
  of 
  zygosphen 
  to 
  lower 
  margin 
  of 
  cup, 
  13.25 
  

  

  Vertical 
  diameter 
  of 
  ball, 
  7.25 
  

  

  Width 
  of 
  neural 
  canal 
  in 
  front, 
  3.75 
  

  

  Height 
  of 
  neural 
  canal 
  in 
  front, 
  2.5 
  

  

  From 
  the 
  Eocene 
  marl 
  of 
  Shark 
  River, 
  Monmouth 
  Co. 
  N. 
  J. 
  

  

  Prof. 
  Marsh 
  regards 
  this 
  and 
  the 
  two 
  species 
  of 
  serpents 
  already 
  described, 
  as 
  representing 
  a 
  genus 
  distinct 
  from 
  

   Palaeophis 
  which 
  he 
  characterizes 
  as 
  follows, 
  ' 
  'Among 
  the 
  most 
  apparent 
  differences 
  between 
  this 
  genus 
  and 
  Palseophis, 
  

   to 
  which 
  it 
  is 
  closely 
  related, 
  are 
  the 
  following: 
  — 
  The 
  base 
  of 
  the 
  neural 
  spine 
  in 
  Dinophis 
  is 
  not 
  co-extensive 
  with 
  the 
  

   supporting 
  arch, 
  but 
  rises 
  a 
  short 
  distance 
  back 
  of 
  the 
  anterior 
  margin 
  of 
  the 
  zygosphen, 
  as 
  in 
  the 
  existing 
  Python. 
  

   The 
  ridge 
  connecting 
  the 
  anterior 
  and 
  posterior 
  zygapophyses 
  is 
  much 
  more 
  developed, 
  and 
  its 
  continuous 
  crest 
  more 
  

   rounded. 
  The 
  sloping 
  sides 
  of 
  the 
  arch 
  above 
  the 
  neural 
  canal 
  are 
  more 
  deeply 
  concave, 
  and 
  an 
  obtuse 
  ridge 
  separ- 
  

   ates 
  the 
  concavity 
  from 
  the 
  anterior 
  zygapophysial 
  notch. 
  The 
  neural 
  canal 
  has 
  a 
  sharp 
  longitudinal 
  ridge 
  on 
  each 
  

   side, 
  which 
  gives 
  its 
  transverse 
  section 
  a 
  trifoliate 
  outline, 
  as 
  in 
  Python. 
  The 
  zygosphen 
  is 
  more 
  excavated 
  ante- 
  

   riorly, 
  and 
  its 
  summit 
  is 
  concave. 
  The 
  zygapophyses 
  are 
  more 
  extended 
  outwardly, 
  and 
  the 
  hypapophysial 
  ridge 
  is 
  

   more 
  prominent." 
  

  

  The 
  most 
  important 
  character 
  here 
  cited 
  appears 
  to 
  be 
  the 
  non-coincidence 
  of 
  the 
  base 
  of 
  the 
  neural 
  spine 
  with 
  

   the 
  neural 
  arch. 
  This 
  character 
  is 
  true 
  of 
  P. 
  littoralis 
  to 
  such 
  a 
  slight 
  degree 
  as 
  to 
  render 
  its 
  importance 
  problemati- 
  

   cal. 
  The 
  other 
  characters 
  adduced, 
  are 
  of 
  a 
  comparative 
  nature, 
  so 
  that 
  until 
  the 
  limits 
  of 
  the 
  proposed 
  genus, 
  if 
  

   valid, 
  can 
  be 
  more 
  fully 
  defined, 
  I 
  retain 
  the 
  species 
  in 
  Palasophis. 
  

  

  AMERT. 
  PHILO. 
  SOC. 
  — 
  VOL. 
  XIV. 
  — 
  58 
  

  

  