﻿HUDSON 
  RIVER 
  BEDS 
  NEAR 
  ALBANY 
  575 
  

  

  § 
  3 
  CRUSTACEA 
  

  

  Ctenobolbina. 
  

  

  Several 
  different 
  forms 
  belonging 
  to 
  this 
  genus, 
  which 
  has, 
  

   hitherto, 
  not 
  been 
  reported 
  from 
  this 
  state, 
  were 
  found 
  at 
  various 
  

   horizons. 
  They 
  are: 
  

  

  1 
  Ctenobolbina 
  cilata. 
  Emmons 
  sp. 
  var. 
  c 
  o 
  r 
  n 
  u 
  t 
  a 
  , 
  

   var. 
  nov. 
  (see 
  pi. 
  2, 
  fig. 
  5-7) 
  

  

  This 
  form 
  differs 
  from 
  the 
  typical 
  Ctenobolbina 
  ciliata 
  

   in 
  having 
  the 
  posterior 
  lobe 
  not 
  so 
  round 
  aud 
  bulbous, 
  and 
  the 
  

   middle 
  lobe 
  produced 
  into 
  a 
  long, 
  stout, 
  blunt 
  spine. 
  The 
  latter 
  

   it 
  has 
  in 
  common 
  with 
  a 
  variety 
  described 
  by 
  Ulrich 
  [Jour. 
  Gin. 
  

   soe. 
  not. 
  hist. 
  1890-91. 
  13 
  :109) 
  a<s 
  Ctenobolbina 
  ciliata 
  

   var. 
  curta, 
  from 
  the 
  lower 
  (Utica) 
  shales 
  of 
  the 
  Cincinnati 
  

   group. 
  It 
  differs 
  from 
  this 
  western 
  relative 
  in 
  being 
  relatively 
  

   longer, 
  having 
  the 
  principal 
  and 
  posterior 
  furrow 
  fully 
  as 
  wide 
  as 
  

   the 
  type 
  of 
  the 
  species 
  and 
  possessing 
  a 
  well 
  developed 
  frill. 
  

   Both 
  forms, 
  which 
  occur 
  in 
  homotaxial 
  beds, 
  represent 
  an 
  early 
  

   divergence 
  from 
  the 
  typical 
  direction 
  of 
  development 
  of 
  the 
  genus 
  

   by 
  the 
  production 
  of 
  an 
  elevated 
  process, 
  thus 
  forming 
  a 
  separate 
  

   section 
  of 
  the 
  species; 
  in 
  a 
  very 
  similar 
  manner 
  as 
  the 
  species 
  

   of 
  Ceratopsis, 
  Ulrich 
  (as 
  B 
  e 
  y 
  r 
  i 
  c 
  h 
  i 
  a 
  oculifera, 
  

   Hall) 
  differ 
  from 
  those 
  of 
  Tetradella 
  by 
  possessing 
  an 
  ele- 
  

   vated 
  process. 
  The 
  remark 
  of 
  Mr 
  Ulrich 
  that 
  these 
  pro-cesses 
  in 
  

   Ceratopsis 
  (loc. 
  eit. 
  p. 
  113) 
  are 
  not 
  a 
  " 
  mere 
  ornament 
  " 
  but 
  

   of 
  a 
  certain 
  classificatory 
  value, 
  would 
  be 
  also 
  pertinent 
  in 
  regard 
  

   to 
  the 
  two 
  horned 
  varieties 
  of 
  Ctenobolbina 
  ciliata; 
  

   and 
  it 
  may 
  at 
  some 
  time 
  become 
  necessary 
  to 
  unite 
  them 
  under 
  

   another 
  generic 
  name. 
  

  

  Dimensions. 
  Length 
  1.45 
  mm, 
  hight 
  .80 
  mm. 
  

  

  Lower 
  L^tica 
  shale 
  of 
  Mechanics 
  ville, 
  Saratoga 
  co. 
  X. 
  Y. 
  Up- 
  

   per 
  Utica 
  shale 
  of 
  Green 
  Island, 
  Albany 
  co. 
  X. 
  Y. 
  

  

  2 
  Ctenobolbina 
  ciliata, 
  Emmons 
  sp. 
  (see 
  pi. 
  2, 
  ti.u. 
  

   8,9). 
  

  

  Typical 
  specimens 
  of 
  Ctenobolbina 
  ciliata 
  have 
  been 
  

   collected 
  at 
  Green 
  Island 
  and 
  at 
  Menands 
  (stations 
  10 
  and 
  11); 
  

  

  