﻿VERTEBRATES. 
  Ill 
  

  

  margin, 
  basal 
  portion 
  channeled 
  and 
  produced 
  downward 
  and 
  out- 
  

   ward 
  in 
  a 
  thin 
  rim, 
  defined 
  above 
  by 
  the 
  narrow 
  inbeveled 
  enamel 
  

   fold 
  ; 
  postero-lateral 
  border 
  converging 
  toward 
  point 
  of 
  inrollment 
  

   somewhat 
  more 
  rapidly 
  than 
  in 
  the 
  case 
  of 
  the 
  opposed 
  mandibular 
  

   teeth, 
  with 
  which 
  it 
  bears 
  much 
  the 
  same 
  characters 
  in 
  respect 
  to 
  

   the 
  basal 
  portion 
  and 
  enamel 
  fold 
  along 
  the 
  upper 
  edge 
  ; 
  inner 
  

   margin 
  most 
  arched 
  round 
  the 
  base 
  of 
  the 
  posterior 
  coronal 
  lobe, 
  in 
  

   front 
  of 
  which 
  it 
  is 
  more 
  or 
  less 
  deflected 
  inward 
  and 
  forward, 
  

   thence 
  gently 
  arching 
  round 
  the 
  anterior 
  prominence 
  to 
  the 
  obtuse 
  

   anterior 
  angle. 
  Coronal 
  region 
  divided 
  into 
  two 
  principal 
  revolving 
  

   elevations, 
  of 
  which 
  the 
  posterior 
  one 
  is 
  much 
  the 
  most 
  prominent, 
  

   occupying 
  about 
  half 
  the 
  lateral 
  diameter 
  of 
  the 
  crown, 
  the 
  broader 
  

   slope 
  rising 
  from 
  the 
  postero-lateral 
  border 
  and 
  culminating 
  nearer 
  

   the 
  anterior 
  side, 
  with 
  a 
  more 
  abrupt 
  slope 
  descending 
  to 
  the 
  median 
  

   depression; 
  the 
  latter 
  presents 
  a 
  broad 
  transversely 
  more 
  or 
  less 
  

   concave 
  area, 
  the 
  surface 
  rising 
  anteriorly 
  into 
  the 
  more 
  or 
  less 
  

   well-defined 
  anterior 
  prominence, 
  thence 
  the 
  slope 
  descends 
  to 
  the 
  

   antero-lateral 
  border. 
  The 
  coronal 
  surface 
  is 
  further 
  marked 
  by 
  

   more 
  or 
  less 
  distinct, 
  though 
  generally 
  obscure 
  and 
  sometimes 
  obso- 
  

   lete 
  subordinate 
  revolving 
  ridges 
  and 
  furrows 
  which 
  are 
  chiefly 
  

   noticeable 
  in 
  the 
  region 
  of 
  the 
  anterior 
  prominence, 
  though 
  some- 
  

   times 
  present 
  in 
  the 
  median 
  depression 
  and 
  the 
  long 
  slope 
  of 
  the 
  

   posterior 
  prominence; 
  more 
  or 
  less 
  distinct 
  transverse 
  rugae 
  dis- 
  

   posed 
  in 
  the 
  same 
  manner 
  noticed 
  in 
  connection 
  with 
  the 
  mandi- 
  

   bular 
  posterior 
  teeth, 
  occur, 
  producing 
  an 
  elegant 
  imbricated 
  orna- 
  

   mentation 
  in 
  the 
  individuals 
  thus 
  distinguished. 
  The 
  latter 
  super- 
  

   ficial 
  feature 
  is, 
  however, 
  obsolete 
  in 
  some 
  species, 
  and 
  which 
  is 
  

   equally 
  applicable 
  to 
  all 
  the 
  other 
  forms 
  of 
  certain 
  species 
  of 
  un- 
  

   doubted 
  congeneric 
  relationship. 
  

  

  In 
  regard 
  to 
  the 
  character 
  of 
  the 
  teeth 
  occupying 
  the 
  extremities 
  

   of 
  the 
  jaws, 
  we 
  can 
  little 
  more 
  than 
  conjecture 
  their 
  identity. 
  

   Amongst 
  the 
  numerous 
  examples 
  of 
  transversely 
  elongate 
  teeth 
  

   which 
  were 
  originally 
  disposed 
  in 
  serial 
  order, 
  and 
  which 
  are 
  recog- 
  

   nized 
  under 
  various 
  generic 
  appellations 
  which 
  in 
  themselves 
  con- 
  

   stitute 
  well-defined 
  groups, 
  there 
  are 
  possibly 
  included 
  forms 
  which 
  

   may 
  have 
  been 
  associated 
  with 
  the 
  teeth 
  under 
  present 
  considera- 
  

   tion. 
  

  

  The 
  generic 
  relations 
  of 
  the 
  forms 
  embraced 
  under 
  the 
  above 
  

   designation 
  are 
  most 
  intimate 
  with 
  Cochliodvs, 
  Agass. 
  Indeed 
  they 
  

   differ, 
  chiefly 
  in 
  the 
  less 
  well 
  defined 
  differentiation 
  of 
  the 
  coronal 
  

   regions, 
  while 
  in 
  Cochliodus 
  these 
  parts 
  are 
  sharply 
  limited, 
  the 
  

  

  