﻿370 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum, 
  

  

  member 
  of 
  this 
  genus, 
  from 
  which, 
  when 
  better 
  understood 
  and 
  

   more 
  precisely 
  restricted, 
  many 
  heterogeneous 
  forms 
  now 
  passing 
  

   under 
  this 
  name 
  must 
  be 
  excluded. 
  The 
  left 
  valve 
  described 
  has 
  

   a 
  height 
  and 
  length 
  of 
  10 
  mm. 
  Upper 
  Hamilton 
  shales. 
  At 
  

   225-350 
  feet 
  in 
  the 
  Livonia 
  Shajft. 
  

  

  Orthothetes 
  bellulus, 
  sp. 
  nov. 
  

  

  Plate 
  IV, 
  figs. 
  2-4. 
  

  

  This 
  very 
  pretty 
  species 
  is 
  of 
  persistently 
  small 
  size 
  and 
  quite 
  

   regular 
  in 
  form, 
  none 
  of 
  the 
  specimens 
  showing 
  umbonal 
  distor- 
  

   tion. 
  The 
  valves 
  are 
  transversely 
  elongate, 
  the 
  hinge-line 
  

   forming 
  the 
  greatest 
  diameter 
  ; 
  and 
  subequally 
  convex. 
  The 
  sur- 
  

   face 
  is 
  covered 
  by 
  eighteen 
  or 
  twenty 
  sharp, 
  narrow, 
  distant 
  

   plications, 
  extending 
  from 
  the 
  margin 
  almost, 
  if 
  not 
  quite, 
  to 
  the 
  

   apex, 
  and 
  in 
  the 
  middle 
  of 
  each 
  of 
  the 
  broad 
  interspaces 
  is 
  a 
  

   smaller 
  and 
  usually 
  very 
  obscure 
  rib 
  ; 
  rarely 
  two 
  of 
  these 
  ribs 
  

   are 
  present. 
  These 
  two 
  series 
  only 
  are 
  to 
  be 
  seen. 
  The 
  lower 
  

   half 
  of 
  the 
  surface 
  is 
  crossed 
  by 
  sharply 
  imbricating 
  concentric 
  

   striae, 
  which 
  are 
  visible 
  only 
  on 
  the 
  interspaces. 
  On 
  the 
  interior 
  

   the 
  characteristic 
  processes 
  of 
  this 
  genus 
  are 
  found. 
  

  

  The 
  length 
  of 
  an 
  average 
  specimen 
  is 
  10 
  mm.; 
  its 
  diameter 
  

   along 
  the 
  hinge, 
  15 
  mm. 
  

  

  This 
  is 
  from 
  the 
  limestone 
  of 
  the 
  Marcellus 
  division 
  at 
  854 
  

   feet 
  in 
  the 
  Shaft, 
  and 
  has 
  not 
  been 
  elsewhere 
  observed. 
  It 
  is 
  

   there 
  associated 
  with 
  specimens 
  of 
  Orthothetes 
  arctostriata 
  of 
  

   small 
  size, 
  finely, 
  subequally 
  plicated 
  and 
  often 
  distorted, 
  but 
  

   there 
  is 
  little 
  indication 
  of 
  any 
  specific 
  connection 
  between 
  these 
  

   two 
  shells. 
  

  

  Chonostrophia 
  reversa, 
  Whitfield 
  (sp.). 
  

   Plate 
  IV, 
  fig. 
  5. 
  

   Among 
  the 
  specimens 
  sent 
  by 
  Dr. 
  Lincoln, 
  of* 
  Geneva, 
  is 
  a 
  

   small 
  fragment 
  of 
  the 
  dark 
  limestone 
  quarried 
  at 
  Union 
  Springs, 
  

   N. 
  Y., 
  which 
  contains 
  a 
  number 
  of 
  valves 
  of 
  this 
  species 
  ; 
  the 
  

   first, 
  I 
  believe, 
  that 
  have 
  been 
  recorded 
  from 
  this 
  State. 
  These 
  

   are 
  all 
  of 
  inferior 
  size 
  to 
  those 
  found 
  at 
  Delaware, 
  Ohio, 
  the 
  

   original 
  locality, 
  as 
  well 
  as 
  to 
  those 
  occurring 
  in 
  the 
  blocks 
  of 
  

   decomposed 
  chert 
  about 
  DeOewville 
  and 
  Cayuga, 
  Province 
  of 
  

   Ontario. 
  

  

  