﻿322 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  conical, 
  acute, 
  and 
  simply 
  curved. 
  Occasionally, 
  however, 
  the 
  

   point 
  is 
  slightly 
  curved 
  forward, 
  giving 
  a 
  hint 
  of 
  the 
  sigmoidal 
  

   curve 
  which 
  is 
  so 
  conspicuous 
  a 
  feature 
  in 
  the 
  great 
  species 
  of 
  

   the 
  Corniferous 
  limestone 
  (0. 
  sigmoides)." 
  a 
  Experience 
  shows 
  

   that 
  the 
  curvature 
  is 
  a 
  variable 
  quantity, 
  and 
  that 
  the 
  sigmoidal 
  

   outline 
  occurs 
  among 
  the 
  Chemung 
  as 
  well 
  as 
  among 
  the 
  Cor- 
  

   niferous 
  specimens; 
  hence 
  the 
  necessity 
  for 
  maintaining 
  0. 
  hop- 
  

   hinsi 
  as 
  a 
  separate 
  species 
  disappears. 
  

  

  ... 
  - 
  ^ 
  

  

  Fig. 
  2, 
  3. 
  Onychodus 
  sigmoides, 
  Newb. 
  Presymphysial 
  teeth— 
  Chemung 
  group. 
  

  

  Prof. 
  Prosser 
  obtained 
  two 
  impressions 
  of 
  the 
  crown 
  from 
  near 
  

   Franklin, 
  but 
  as 
  these 
  were 
  imperfect 
  we 
  have 
  selected 
  two 
  other 
  

   specimens 
  from 
  the 
  same 
  locality 
  for 
  purposes 
  of 
  illustration. 
  

   The 
  original 
  of 
  fig. 
  2 
  belongs 
  to 
  the 
  Dyer 
  collection, 
  in 
  the 
  

   Museum 
  of 
  comparative 
  zoology 
  at 
  Cambridge, 
  and 
  the 
  other 
  is 
  

   preserved 
  in 
  the 
  collections 
  of 
  the 
  state 
  museum 
  at 
  Albany. 
  

  

  Other 
  specimens 
  of 
  fish-remains 
  from 
  the 
  New 
  York 
  Chemung 
  

   have 
  been 
  found 
  by 
  H. 
  S. 
  Williams 
  near 
  Kushford, 
  Allegany 
  

   co., 
  and 
  comprise 
  teeth, 
  Ctenodus 
  nelsoni 
  and 
  C. 
  levis 
  (?), 
  be- 
  

   sides 
  " 
  numerous 
  fragments 
  of 
  fish-bones 
  and 
  a 
  fish 
  -jaw." 
  a 
  As 
  

   one 
  of 
  the 
  teeth 
  is 
  doubtfully 
  determinable 
  as 
  Ctenodus 
  levis, 
  the 
  

   alternative 
  title 
  C. 
  alleghaniensis 
  is 
  proposed 
  for 
  it 
  by 
  Prof. 
  

  

  oLoc. 
  clt. 
  (1889) 
  p. 
  99. 
  

  

  