﻿196 
  PALEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  bed 
  stratum 
  near 
  the 
  base 
  of 
  the 
  Carboniferous 
  series 
  nt 
  Santa 
  P6, 
  

   New 
  Mexico. 
  The 
  state 
  of 
  preservation 
  of 
  the 
  specimens, 
  although 
  

   not 
  perfect, 
  is 
  sufficient 
  to 
  afford 
  the 
  basis 
  of 
  comparison 
  with 
  the 
  

   allied 
  species 
  Orthopleu/rodnu 
  carbonarius, 
  occurring 
  in 
  the 
  

   Measures 
  of 
  the 
  Mississippi 
  Valley. 
  While 
  the 
  present 
  species 
  is 
  

   smaller 
  in 
  size, 
  the 
  mandibular 
  posterior 
  teeth 
  differ 
  from 
  the 
  latter 
  

   in 
  their 
  proportionately 
  greater 
  breadth 
  as 
  compared 
  with 
  the 
  h 
  

   along 
  the 
  antero-lateral 
  border: 
  the 
  maxillary 
  posterior 
  teeth 
  may 
  

   be 
  distinguished 
  by 
  the 
  apparently 
  less 
  oblique 
  course 
  of 
  the 
  

   nal 
  ridge, 
  while 
  the 
  surface 
  punctation 
  is 
  much 
  the 
  same 
  in 
  both 
  

   species, 
  the 
  puncta 
  1 
  , 
  perhaps, 
  more 
  widely 
  spaced 
  in 
  the 
  New 
  Mex- 
  

   ican 
  teeth. 
  Its 
  resemblances 
  with 
  the 
  above 
  species 
  is 
  more 
  inti- 
  

   mate 
  than 
  with 
  Orthopleurodus 
  convexus, 
  although 
  there 
  is 
  a 
  marked 
  

   similarity 
  in 
  the 
  maxillary 
  posterior 
  forms, 
  as 
  indicated 
  by 
  the 
  

   imperfectly 
  worn 
  examples. 
  

  

  Geological 
  position 
  and 
  locality: 
  From 
  the 
  fish-bed 
  layer 
  near 
  the 
  

   base 
  of 
  the 
  Carboniferous 
  series, 
  associated 
  with 
  other 
  Lower 
  Car- 
  

   boniferous 
  fish-remains; 
  near 
  Santa 
  Fe, 
  New 
  Mexico. 
  

  

  