﻿VEETEBEATES. 
  137 
  

  

  General 
  outline 
  trigonal, 
  lateral 
  diameter 
  proportionately 
  short, 
  

   compared 
  to 
  the 
  length, 
  which 
  it 
  but 
  little 
  exceeds 
  ; 
  general 
  course 
  of 
  

   inner 
  margin 
  nearly 
  at 
  right-angles 
  with 
  the 
  antero-lateral 
  border, 
  

   somewhat 
  sinuous 
  and 
  broadly 
  rounded, 
  and 
  somewhat 
  sharply 
  so 
  

   in 
  passing 
  the 
  angle 
  of 
  the 
  principal 
  coronal 
  prominence, 
  thence 
  

   pursuing 
  a 
  slightly 
  curved 
  course 
  into 
  the 
  produced 
  posterior 
  angle; 
  

   antero-lateral 
  border 
  nearly 
  straight 
  or 
  very 
  gently 
  curved 
  sigmoidally 
  

   in 
  passing 
  into 
  the 
  extremely-inrolled 
  outer 
  extremity; 
  basal 
  portion 
  

   nearly 
  vertical, 
  very 
  deep, 
  and 
  defined 
  above 
  by 
  the 
  usual 
  narrow 
  

   enamel 
  fold, 
  which 
  forms 
  an 
  inbeveled 
  coping 
  projecting 
  considerably 
  

   beyond 
  the 
  basal 
  wall 
  ; 
  postero-lateral 
  border 
  rapidly 
  converging 
  to- 
  

   ward 
  the 
  outer 
  margin, 
  making 
  an 
  angle 
  of 
  about 
  50° 
  with 
  the 
  anterior 
  

   border; 
  condition 
  of 
  coronal 
  fold 
  and 
  basal 
  edge 
  not 
  determinable. 
  

   Coronal 
  region 
  strongly 
  arched 
  in 
  the 
  direction 
  of 
  inrollment, 
  and 
  

   principally 
  occupied 
  by 
  the 
  longitudinal 
  prominences 
  ; 
  principal 
  ridge 
  

   nearly 
  median, 
  strongly 
  arched 
  transversely 
  and 
  defined 
  by 
  a 
  more 
  

   or 
  less 
  distinct 
  angulation 
  from 
  the 
  broad, 
  posterior 
  depression, 
  

   which 
  is 
  bordered 
  by 
  the 
  gentle 
  acclivity 
  rising 
  into 
  the 
  postero- 
  

   lateral 
  border 
  of 
  the 
  alate 
  expansion; 
  anterior 
  ridge 
  almost 
  equally 
  

   prominent 
  and 
  similar 
  in 
  contour 
  to 
  the 
  principal 
  ridge, 
  from 
  which 
  

   it 
  is 
  separated 
  by 
  a 
  deep 
  depression 
  of 
  nearly 
  equal 
  breadth, 
  with 
  

   very 
  steep, 
  concave 
  walls, 
  slightly 
  flattened 
  along 
  the 
  rounded 
  crest, 
  

   the 
  slope 
  in 
  front 
  descending, 
  in 
  a 
  similar 
  slight 
  concavity, 
  to 
  the 
  

   antero-lateral 
  border, 
  which 
  is 
  margined 
  by 
  a 
  very 
  narrow 
  fold 
  of 
  the 
  

   coronal 
  enamel. 
  Surface 
  minutely 
  and 
  densely 
  punctate, 
  with 
  faint 
  

   transverse 
  lines 
  along 
  the 
  less 
  worn 
  inner 
  margin, 
  otherwise 
  des- 
  

   titute 
  of 
  the 
  rugosities 
  common 
  to 
  nearly 
  all 
  its 
  congeners. 
  Trans- 
  

   verse 
  diameter 
  at 
  the 
  inner 
  margin 
  about 
  35 
  mm. 
  ; 
  length 
  of 
  antero- 
  

   lateral 
  border 
  to 
  point 
  of 
  inrollment, 
  25 
  mm. 
  ; 
  ditto 
  along 
  principal 
  

   coronal 
  ridge, 
  about 
  30 
  mm. 
  ; 
  depth 
  of 
  antero-lateral 
  border, 
  5 
  mm. 
  

  

  The 
  outer 
  portion, 
  as 
  also 
  the 
  postero-lateral 
  border, 
  is 
  mutilated, 
  

   exposing 
  to 
  view 
  the 
  remarkable 
  inrollment 
  which 
  amounts 
  to 
  one 
  

   and 
  a 
  half 
  revolutions, 
  with 
  a 
  short 
  convoluted 
  apex. 
  The 
  form 
  

   described 
  differs 
  in 
  so 
  marked 
  a 
  degree 
  from 
  other 
  species 
  of 
  the 
  

   genus 
  as 
  not 
  to 
  require 
  detailed 
  comparison 
  ; 
  it 
  is 
  chiefly 
  distinguished 
  

   from 
  allied 
  species 
  by 
  the 
  regularly 
  arched 
  coronal 
  ridges, 
  deep 
  

   narrow 
  median 
  depression, 
  and 
  abbreviated 
  transverse 
  diameter. 
  

  

  This 
  largest 
  American 
  representative 
  of 
  the 
  genus, 
  and 
  I 
  believe 
  

   the 
  largest 
  species 
  known, 
  is 
  dedicated 
  to 
  Professor 
  Worthen, 
  the 
  

   venerable 
  director 
  of 
  the 
  geological 
  survey. 
  

  

  Geological 
  position 
  and 
  locality: 
  Chester 
  limestone, 
  Chester, 
  111. 
  

  

  