﻿W. 
  J. 
  Sinclair 
  — 
  A 
  New 
  Labyrinth 
  odont. 
  319 
  

  

  Art. 
  XXVIII. 
  — 
  A 
  New 
  Labyrinthodont 
  from 
  the 
  Triassic 
  

   of 
  Pennsylvania 
  ; 
  by 
  W. 
  J. 
  Sinclair. 
  

  

  Remains 
  of 
  vertebrates 
  from 
  the 
  rocks 
  of 
  the 
  Newark 
  

   group 
  are 
  so 
  rare 
  that 
  every 
  additional 
  specimen 
  obtained 
  from 
  

   them 
  cannot 
  fail 
  to 
  be 
  of 
  interest. 
  The 
  material 
  which 
  forms 
  

   the 
  subject 
  of 
  the 
  following 
  note 
  w 
  T 
  as 
  collected 
  by 
  Professor 
  

   Gilbert 
  'Van 
  Ingen 
  and 
  the 
  writer 
  from 
  the 
  locally 
  basal 
  beds 
  of 
  

   the 
  Norristown 
  shale 
  at 
  Holicong, 
  Bucks 
  County," 
  Pennsylvania. 
  

   It 
  comprises 
  the 
  front 
  part 
  of 
  the 
  left 
  half 
  of 
  the 
  lower 
  jaw 
  

   of 
  a 
  large 
  Stegocephalian, 
  No. 
  12302 
  Princeton 
  University 
  

   Geological 
  Museum, 
  comparable 
  in 
  size 
  with 
  Mastodon 
  saur 
  us, 
  

   and 
  apparently 
  pertaining 
  to 
  an 
  undescribed 
  genus 
  and 
  species 
  

   for 
  which 
  the 
  name 
  Catamops 
  jpaludosus 
  is 
  proposed. 
  Two 
  

   large 
  pieces, 
  evidently 
  belonging 
  to 
  the 
  back 
  of 
  the 
  jaw, 
  do 
  

   not 
  make 
  contact 
  with 
  the 
  tooth-bearing 
  portion 
  of 
  the 
  ramus 
  

   and 
  have 
  been 
  omitted 
  in 
  the 
  drawing 
  (tig. 
  1). 
  They 
  are 
  some- 
  

   what 
  fragmentary 
  and 
  so 
  heavily 
  covered 
  with 
  matrix 
  that 
  

   little 
  or 
  nothing 
  can 
  be 
  made 
  of 
  them. 
  

  

  The 
  jaw 
  was 
  found 
  in 
  a 
  red 
  shale 
  abounding 
  in 
  impressions 
  

   of 
  large 
  horse-tail 
  rushes 
  which 
  are 
  observable 
  on 
  the 
  surface 
  

   of 
  the 
  hard 
  siliceous 
  capsule 
  investing 
  the 
  bone 
  (whence 
  

   Oalamops, 
  " 
  reed-face 
  "). 
  This 
  capsule 
  is 
  of 
  variable 
  thickness 
  

   up 
  to 
  half 
  an 
  inch 
  or 
  so, 
  is 
  apparently 
  siliceous, 
  of 
  radiate 
  

   structure, 
  and 
  is 
  applied 
  so 
  closely 
  to 
  the 
  outer 
  surface 
  of 
  the 
  

   bone, 
  and 
  has 
  become 
  so 
  much 
  a 
  part 
  of 
  it, 
  that 
  its 
  removal 
  

   has 
  proved 
  impracticable, 
  especially 
  as 
  the 
  bone-substance 
  is 
  

   quite 
  soft 
  and 
  spongy, 
  owing 
  to 
  partial 
  solution. 
  

  

  The 
  portion 
  of 
  the 
  jaw 
  preserved 
  is 
  straight 
  lengthwise, 
  

   except 
  toward 
  the 
  forward 
  end 
  where 
  it 
  curves 
  inward 
  toward 
  

   the 
  symphysis. 
  Here 
  the 
  matrix 
  is 
  broken 
  off 
  and 
  bone 
  tissue 
  

   exposed 
  below 
  the 
  base 
  of 
  one, 
  or 
  perhaps 
  two 
  teeth. 
  The 
  

   upper 
  margin 
  of 
  the 
  ramus 
  carries 
  a 
  series 
  of 
  seventeen 
  large 
  

   teeth 
  without 
  sockets. 
  Perhaps 
  an 
  additional 
  small 
  tooth 
  or 
  

   two 
  occurs 
  in 
  front 
  of 
  the 
  first 
  large 
  tooth 
  in 
  the 
  series. 
  The 
  

   matrix 
  has 
  been 
  chipped 
  off 
  the 
  tips 
  of 
  several 
  of 
  the 
  teeth 
  

   giving 
  some 
  rather 
  imperfect 
  cross 
  sections. 
  These 
  have 
  been 
  

   supplemented 
  by 
  a 
  thin 
  section 
  of 
  the 
  penultimate 
  tooth, 
  cut 
  

   transversely. 
  Apparently 
  the 
  teeth 
  are 
  without 
  enamel, 
  with 
  

   smooth 
  or 
  but 
  slightly 
  grooved 
  crowns, 
  circular 
  in 
  cross 
  section 
  

   at 
  the 
  base 
  and, 
  in 
  the 
  case 
  of 
  some 
  of 
  them, 
  with 
  the 
  crown 
  

   slightly 
  flattened 
  laterally 
  toward 
  the 
  tip, 
  with 
  acute 
  anterior 
  

   and 
  posterior 
  edges. 
  In 
  thin 
  section, 
  cut 
  transversely 
  to 
  the 
  

   crown, 
  radial 
  prolongations 
  of 
  the 
  pulp 
  cavity 
  are 
  seen 
  toward 
  

   which 
  numerous 
  tine 
  dentine 
  tubules 
  seem 
  to 
  converge 
  from 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLIII, 
  No. 
  256,— 
  April, 
  1917. 
  

  

  22 
  

  

  