﻿VEETEBEATES. 
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  lateral 
  surfaces 
  are 
  occupied 
  by 
  more 
  or 
  less 
  regular, 
  prominent, 
  

   rounded, 
  smooth 
  enamel-coated 
  costse 
  separated 
  by 
  narrow 
  intercos- 
  

   tal 
  furrows, 
  the 
  cost® 
  comprised 
  within 
  the 
  narrow 
  compressed 
  belt 
  

   along 
  the 
  posterolateral 
  margins 
  being 
  more 
  slender, 
  and 
  toward 
  

   the 
  base 
  those 
  occupying 
  the 
  body 
  of 
  the 
  spine 
  bifurcate, 
  the 
  ante- 
  

   rior 
  ridge 
  especially 
  sending 
  off 
  frequent 
  slender 
  branches 
  to 
  the 
  

   dorsal 
  line. 
  The 
  lower 
  part 
  of 
  the 
  spine 
  shows 
  distinct 
  lines 
  of 
  

   growth 
  exactly 
  corresponding 
  in 
  curvature 
  to 
  the 
  dorsal 
  line 
  and 
  

   forming 
  faint 
  oblique 
  annular 
  ridges 
  crossing 
  the 
  costse 
  at 
  irreg- 
  

   ular 
  intervals 
  ; 
  otherwise 
  the 
  costae 
  are 
  destitute 
  of 
  ornamentation, 
  

   the 
  occurrence 
  of 
  the 
  oblique 
  ridges 
  mentioned 
  not 
  producing 
  an 
  

   effect 
  comparable 
  with 
  that 
  of 
  the 
  tuberculated 
  Ctenacanthi. 
  The 
  

   dorsal 
  line 
  makes 
  an 
  angle 
  of 
  40°, 
  and 
  less, 
  with 
  the 
  anterior 
  edge, 
  

   somewhat 
  sigmoidal 
  in 
  curvature, 
  rising 
  well 
  up 
  the 
  postero-lateral 
  

   angles 
  ; 
  inserted 
  base 
  deep, 
  surface 
  irregularly 
  striato-punctate. 
  

   Length 
  of 
  spine 
  12 
  centimetres 
  ; 
  greatest 
  transverse 
  breadth 
  13 
  mili- 
  

   metres. 
  

  

  The 
  above 
  described 
  species 
  is 
  represented 
  by 
  a 
  unique 
  and 
  nearly 
  

   perfect 
  specimen, 
  which 
  was 
  discovered 
  by 
  Mr. 
  A. 
  S. 
  Tiffany, 
  to 
  

   whom 
  we 
  are 
  indebted 
  for 
  the 
  opportunity 
  to 
  examine 
  many 
  inter- 
  

   esting 
  fish-remains 
  from 
  our 
  Carboniferous 
  and 
  Devonian 
  formations. 
  

   In 
  accordance 
  with 
  our 
  understanding 
  of 
  the 
  values 
  to 
  be 
  ascribed 
  

   to 
  external 
  characters 
  in 
  determining 
  the 
  limits 
  of 
  genera 
  as 
  repre- 
  

   sented 
  by 
  the 
  fin-defenses 
  of 
  these 
  early 
  Selachians, 
  the 
  present 
  

   spine 
  does 
  not 
  reveal 
  any 
  feature 
  markedly 
  at 
  variance 
  with 
  those 
  

   ascribed 
  to 
  Acondylacanthus, 
  with 
  which 
  we 
  have 
  identified 
  it. 
  

   Specifically, 
  however, 
  it 
  offers 
  tangible 
  and 
  most 
  pronounced 
  pecu- 
  

   liarities, 
  such 
  indeed 
  as 
  may 
  not 
  readily 
  escape 
  notice 
  even 
  in 
  

   fragmentary 
  material, 
  when 
  sufficient 
  remains 
  to 
  show 
  its 
  peculiar 
  

   superficial 
  features 
  and 
  the 
  outline 
  of 
  its 
  transverse 
  section. 
  Were 
  

   it 
  possible 
  to 
  decide 
  the 
  association 
  of 
  teeth 
  and 
  fin 
  spines, 
  we 
  

   might 
  in 
  many 
  instances 
  find 
  much 
  less 
  dissimilarity 
  in 
  the 
  fin 
  de- 
  

   fenses 
  of 
  different 
  genera 
  than 
  that 
  indicated 
  by 
  their 
  respective 
  

   dentition. 
  But 
  lacking 
  these 
  facts 
  relating 
  to 
  generic 
  identity, 
  we 
  

   must 
  seek 
  to 
  discover 
  such 
  characteristics 
  as 
  seem 
  to 
  have 
  a 
  com- 
  

   mon 
  significance 
  and 
  by 
  which 
  these 
  varied 
  remains 
  may 
  be 
  brought 
  

   into 
  such 
  natural 
  groups 
  as 
  appear 
  most 
  consistent 
  with 
  the 
  fea- 
  

   tures 
  they 
  possess 
  in 
  common. 
  

  

  Geological 
  position 
  and 
  locality: 
  Upper 
  Coal 
  Measures; 
  upper 
  

   limestone 
  at 
  Peru, 
  Illinois. 
  

  

  