﻿VERTEBRATES. 
  151 
  

  

  Mr. 
  Van 
  Home 
  has 
  obtained 
  from 
  the 
  Warsaw 
  beds 
  in 
  the 
  neigh- 
  

   borhood 
  of 
  the 
  mouth 
  of 
  Piasa 
  creek, 
  above 
  Alton, 
  two 
  specimens 
  

   of 
  the 
  maxillary 
  terminal 
  form, 
  but, 
  unfortunately, 
  they 
  are 
  in 
  too 
  

   imperfect 
  a 
  state 
  of 
  preservation 
  for 
  the 
  satisfactory 
  determination 
  

   of 
  their 
  specific 
  identity. 
  They 
  are 
  quite 
  peculiar 
  for 
  the 
  exceed- 
  

   ingly 
  crowded 
  punctation, 
  and 
  one 
  of 
  the 
  specimens 
  shows 
  quite 
  

   distinct 
  widely 
  spaced 
  transverse 
  undulations 
  traversing 
  the 
  coronal 
  

   surface, 
  recalling 
  Deltodus 
  cingvlatus, 
  N. 
  and 
  W., 
  of 
  the 
  Chester 
  

   limestone. 
  

  

  The 
  Warsaw 
  beds 
  at 
  Warsaw 
  have 
  also 
  yielded 
  a 
  large 
  example 
  

   of 
  the 
  mandibular 
  median 
  form, 
  which 
  is 
  difficult 
  to 
  distinguish 
  

   from 
  the 
  same 
  form 
  associated 
  with 
  Deltodus 
  occidentalis, 
  except 
  that 
  

   the 
  principal 
  ridge 
  is 
  very 
  perceptibly 
  more 
  broadly 
  rounded 
  or 
  

   depressed 
  along 
  the 
  crest 
  and 
  the 
  alate 
  lobe 
  relatively 
  stronger 
  and 
  

   a 
  little 
  more 
  prominent 
  ; 
  the 
  antero-lateral 
  border 
  is 
  broken 
  away 
  

   so 
  that 
  it 
  is 
  not 
  clear 
  how 
  closely 
  it 
  resembles 
  the 
  typical 
  examples 
  

   of 
  the 
  species 
  with 
  which 
  it 
  is 
  here 
  compared 
  as 
  well 
  as 
  its 
  

   resemblance 
  to 
  the 
  form 
  referred 
  to 
  under 
  the 
  head 
  of 
  D. 
  trilobus, 
  

   from 
  which 
  it 
  differs 
  in 
  its 
  more 
  robust 
  build 
  and 
  less 
  emphasized 
  

   coronal 
  prominence. 
  

  

  The 
  specific 
  identity 
  of 
  the 
  teeth 
  above 
  alluded 
  to, 
  if 
  it 
  proves 
  to 
  

   be 
  well 
  founded, 
  is 
  of 
  enhanced 
  interest 
  on 
  account 
  of 
  the 
  evidence 
  

   they 
  furnish 
  on 
  the 
  perpetuation 
  of 
  the 
  species 
  unchanged 
  for 
  so 
  

   long 
  a 
  period 
  as 
  that 
  involved 
  in 
  the 
  deposition 
  of 
  probably 
  not 
  

   less 
  than 
  300 
  feet 
  of 
  sediments 
  included 
  between 
  tbe 
  earlier 
  and 
  

   the 
  latest 
  deposits 
  in 
  which 
  its 
  remains 
  have 
  been 
  found, 
  while 
  

   other 
  species 
  subsequently 
  appear 
  both 
  in 
  the 
  Warsaw 
  and 
  St 
  

   Louis 
  formations. 
  

  

  Geological 
  position 
  and 
  localities 
  : 
  Warsaw 
  limestone 
  ; 
  Warsaw, 
  

   Alton, 
  and 
  Jersey 
  county, 
  111. 
  : 
  St. 
  Louis 
  limestone 
  ; 
  Alton, 
  and 
  

   Monroe 
  county, 
  111. 
  

  

  Deltodus 
  parvus, 
  St. 
  J. 
  and 
  W. 
  

  

  PL 
  IX, 
  Fig. 
  1-5. 
  

  

  Teeth 
  of 
  small 
  size. 
  Mandibular 
  posterior 
  form 
  sub-trapezoidal 
  in 
  

   outline, 
  rather 
  strongly 
  arched 
  and 
  inrolled, 
  usually 
  a 
  little 
  longer 
  

   than 
  wide. 
  Antero-lateral 
  border 
  with 
  a 
  slight 
  incurved 
  outline, 
  

   basal 
  portion 
  slightly 
  channeled 
  and 
  limited 
  above 
  by 
  the 
  narrow 
  

   enamel 
  fold; 
  inner 
  margin 
  forming 
  nearly 
  a 
  right 
  angle 
  with 
  the 
  

  

  