﻿W. 
  J. 
  Sinclair 
  — 
  A 
  New 
  Labyrinthodont. 
  321 
  

  

  the 
  outer 
  wall 
  of 
  the 
  tooth. 
  Labyrinthine 
  infoldings 
  of 
  cement 
  

   have 
  not 
  been 
  made 
  out. 
  The 
  radiating 
  pulp 
  canals 
  are 
  

   especially 
  well 
  shown 
  on 
  the 
  tenth 
  tooth 
  in 
  series, 
  counting 
  

   forward 
  from 
  the 
  back 
  of 
  the 
  jaw, 
  where 
  an 
  attempt 
  at 
  remov- 
  

   ing 
  the 
  exceedingly 
  hard 
  matrix 
  resulted 
  in 
  chipping 
  off 
  the 
  

   outer 
  wall 
  and 
  exposing 
  the 
  ends 
  of 
  the 
  pulp 
  canals 
  which 
  ap- 
  

   pear 
  as 
  a 
  series 
  of 
  vertical 
  grooves. 
  The 
  anterior 
  teeth 
  are 
  

   somewhat 
  variable 
  in 
  height, 
  but 
  none 
  seem 
  to 
  be 
  specially 
  

   enlarged 
  unless 
  the 
  tooth 
  supported 
  on 
  the 
  base 
  exposed 
  at 
  the 
  

   broken 
  symphysial 
  margin 
  might 
  have 
  been 
  so. 
  The 
  last 
  three 
  

   teeth 
  are 
  much 
  shorter 
  than 
  the 
  rest. 
  Although 
  their 
  tips 
  are 
  

   broken 
  off, 
  their 
  bases 
  are 
  considerably 
  higher 
  than 
  those 
  of 
  

   the 
  teeth 
  in 
  front 
  owing 
  to 
  a 
  sudden 
  increase 
  in 
  depth 
  of 
  the 
  

   jaw. 
  Externally, 
  the 
  teeth 
  anterior 
  to 
  these 
  three 
  are 
  sup- 
  

   ported 
  by 
  a 
  flange 
  from 
  the 
  jaw, 
  only 
  their 
  tips 
  projecting 
  

   above 
  it. 
  

  

  Owing 
  to 
  the 
  thick 
  capsule 
  of 
  hard 
  material 
  adhering 
  to 
  the 
  

   bone, 
  none 
  of 
  the 
  jaw 
  elements 
  can 
  be 
  made 
  out, 
  which 
  renders 
  

   difficult 
  a 
  comparison 
  with 
  forms 
  hitherto 
  known. 
  On 
  the 
  

   outer 
  side 
  of 
  the 
  jaw, 
  the 
  matrix 
  has 
  an 
  irregular 
  hummocky 
  

   surface 
  suggestive 
  of 
  pittings 
  in 
  the 
  bone. 
  The 
  latter 
  is 
  flat 
  

   behind 
  and 
  slightly 
  convex 
  in 
  front 
  in 
  vertical 
  section. 
  In- 
  

   ternally 
  and 
  toward 
  the 
  back 
  of 
  the 
  jaw, 
  a 
  wedge-shaped 
  

   depression 
  is 
  inclosed 
  between 
  a 
  strongly 
  convex 
  ridge 
  above 
  

   and 
  a 
  lower 
  ridge 
  below. 
  This 
  depression 
  fades 
  out 
  anteriorly 
  

   until 
  below 
  the 
  eleventh 
  tooth, 
  counting 
  forward 
  from 
  behind, 
  

   the 
  jaw 
  is 
  strongly 
  convex 
  in 
  vertical 
  section. 
  Its 
  lower 
  mar- 
  

   gin 
  is 
  broadly 
  concave 
  upward, 
  increasing 
  in 
  curvature 
  toward 
  

   the 
  symphysis. 
  

  

  Calamops 
  is 
  larger 
  than 
  any 
  labyrinthodont 
  hitherto 
  

   described 
  from 
  the 
  Newark 
  group 
  and 
  is 
  the 
  largest 
  amphibian 
  

   thus 
  far 
  reported 
  from 
  the 
  Triassic 
  of 
  North 
  America. 
  The 
  

   fragment 
  figured 
  has 
  an 
  extreme 
  length, 
  measured 
  in 
  a 
  straight 
  

   line, 
  of 
  446 
  millimeters 
  ; 
  at 
  its 
  narrowest 
  part 
  below 
  the 
  four- 
  

   teenth 
  tooth, 
  counting 
  forward 
  from 
  the 
  last, 
  the 
  depth 
  of 
  the 
  

   jaw 
  is 
  55 
  millimeters 
  ; 
  measured 
  vertically 
  below 
  the 
  base 
  of 
  

   the 
  last 
  tooth 
  it 
  is 
  118 
  millimeters. 
  Owing 
  to 
  the 
  heavy 
  coat- 
  

   ing 
  of 
  matrix, 
  not 
  even 
  approximate 
  figures 
  for 
  the 
  thickness 
  

   can 
  be 
  given. 
  The 
  longest 
  tooth 
  rises 
  43 
  millimeters 
  above 
  

   the 
  inner, 
  upper 
  margin 
  of 
  the 
  jaw 
  and 
  is 
  about 
  16 
  milli- 
  

   meters 
  in 
  diameter 
  anteroposterioriy 
  at 
  the 
  base. 
  

  

  Princeton 
  University, 
  

  

  Department 
  of 
  Geology, 
  

   January 
  1917. 
  

  

  