﻿VEETEBEATES. 
  183 
  

  

  wavy, 
  coalescing 
  and 
  bifurcating 
  sharp 
  transverse 
  rugae. 
  The 
  linear 
  

   parallel 
  disposition 
  of 
  the 
  punctse 
  may 
  be 
  detected 
  even 
  in 
  much 
  

   worn 
  surfaces, 
  though, 
  as 
  might 
  be 
  expected, 
  it 
  is 
  here 
  less 
  apparent 
  ; 
  

   and 
  toward 
  the 
  outer 
  extremity, 
  in 
  excessively 
  worn 
  teetb, 
  the 
  

   surface 
  structure 
  does 
  not 
  differ 
  from 
  that 
  usually 
  met 
  with 
  in 
  the 
  

   Cochliodonts. 
  

  

  The 
  teeth 
  above 
  attributed 
  to 
  the 
  posterior 
  position 
  on 
  the 
  max- 
  

   illary 
  are 
  comparable 
  to 
  Xystrodus 
  striatus, 
  Agass., 
  from 
  which 
  they 
  

   are 
  chiefly 
  recognizable 
  by 
  the 
  proportionately 
  narrower 
  outline 
  and 
  

   perceptibly 
  less 
  expanded 
  alation. 
  The 
  opposed 
  teeth, 
  as 
  herein 
  

   interpreted, 
  are 
  also 
  intimately 
  allied 
  to 
  a 
  form 
  associated 
  with 
  X. 
  

   striatus, 
  of 
  which 
  the 
  collections 
  of 
  Lord 
  Ennisldllen 
  at 
  Florence 
  

   Court 
  contain 
  numerous 
  representatives. 
  The 
  latter 
  form, 
  with 
  the 
  

   original 
  X. 
  striatus, 
  presents 
  exactly 
  the 
  same 
  association 
  of 
  forms 
  

   which 
  we 
  have 
  attempted 
  to 
  ascribe 
  to 
  the 
  more 
  prominent 
  dental 
  

   elements 
  of 
  this 
  genus, 
  as 
  represented 
  in 
  the 
  present 
  species. 
  The 
  

   Chester 
  tooth, 
  however, 
  differs 
  from 
  the 
  extremely 
  alate 
  examples 
  

   from 
  Armagh 
  hi 
  its 
  great 
  length 
  as 
  compared 
  with 
  the 
  inner 
  trans- 
  

   verse 
  diameter, 
  or 
  in 
  directly 
  opposite 
  character 
  to 
  the 
  distinguishing 
  

   features 
  noted 
  in 
  connection 
  with 
  the 
  maxillary 
  teeth. 
  

  

  Geological 
  position 
  and 
  localities 
  : 
  Chester 
  limestone 
  ; 
  Chester, 
  and 
  

   Monroe 
  county, 
  111. 
  

  

  Xystrodus 
  bellulus, 
  St. 
  J. 
  and 
  W. 
  

   pi. 
  viii, 
  rig. 
  3. 
  

   The 
  form 
  here 
  indicated 
  is 
  represented 
  by 
  a 
  small 
  tooth, 
  some- 
  

   what 
  imperfect 
  at 
  the 
  apical 
  extremity 
  and 
  along 
  the 
  oblique 
  border 
  

   and 
  the 
  inner 
  margin, 
  pertaining 
  to 
  the 
  left 
  ramus 
  of 
  the 
  maxillary. 
  

   Very 
  gently 
  arched 
  longitudinally, 
  narrow 
  wedge-shaped 
  in 
  out- 
  

   line 
  and 
  very 
  gradually 
  tapering, 
  crown 
  broadly 
  arched 
  laterally, 
  an 
  

   obscure 
  angulation 
  in 
  the 
  median 
  depression 
  defining 
  the 
  anterior 
  

   coronal 
  prominence 
  from 
  the 
  narrow, 
  slightly 
  upraised 
  alate 
  expan- 
  

   sion 
  along 
  the 
  oblique 
  border; 
  along 
  the 
  straight 
  or 
  antero 
  -lateral 
  

   border 
  the 
  crown 
  is 
  rounded 
  and 
  then 
  sharply 
  inbeveled 
  from 
  the 
  

   distinct 
  angulation, 
  the 
  narrow 
  enamel 
  fold 
  limited 
  by 
  a 
  slight 
  fur- 
  

   row, 
  beneath 
  which 
  the 
  basal 
  rim 
  is 
  gently 
  produced 
  outward 
  and 
  

   downward, 
  terminating 
  in 
  a 
  thin, 
  rounded 
  edge. 
  The 
  inferior 
  sur- 
  

   face 
  of 
  the 
  tooth 
  is 
  smooth, 
  approximately 
  conforming 
  in 
  contour 
  

   to 
  that 
  of 
  the 
  crown. 
  The 
  coronal 
  surface 
  is 
  beautifully 
  marked 
  by 
  

  

  