﻿180 
  Twenty-eighth 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  outer 
  chambers, 
  beyond 
  which 
  the 
  shell 
  is 
  marked 
  by 
  gentle 
  

   undulations 
  or 
  lines 
  of 
  growth 
  ; 
  the 
  space 
  between 
  the 
  ambula- 
  

   tions 
  regularly 
  concave. 
  In 
  well-preserved 
  specimens 
  (seldom 
  

   in 
  others) 
  there 
  are 
  finer 
  surface-markings 
  consisting 
  of 
  

   longitudinal 
  strise 
  of 
  which 
  there 
  are 
  five 
  in 
  the 
  space 
  of 
  one 
  

   millimetre 
  ; 
  these 
  are 
  crossed 
  by 
  finer 
  concentric 
  strise. 
  

  

  This 
  species 
  differs 
  from 
  any 
  known 
  form 
  in 
  the 
  Niagara 
  

   group, 
  by 
  its 
  more 
  slender 
  and 
  gradually 
  enlarging 
  volutions. 
  

  

  