﻿152 
  Twenty-eighth 
  Keport 
  on 
  the 
  State 
  Museum. 
  

  

  moderately 
  convex 
  for 
  more 
  than 
  half 
  the 
  length, 
  and 
  rap- 
  

   idly 
  descending 
  to 
  the 
  margin. 
  Hinge 
  area 
  narrow 
  ; 
  foramen 
  

   triangular, 
  width 
  about 
  equal 
  to 
  the 
  height 
  ; 
  covered 
  by 
  a 
  

   strong 
  deltidial 
  callosity. 
  The 
  crenulations 
  or 
  teeth 
  on 
  the 
  

   interior 
  margin 
  are 
  oblique, 
  diverging 
  from 
  the 
  beak, 
  extend- 
  

   ing 
  from 
  the 
  foramen 
  less 
  than 
  half-way 
  to 
  the 
  cardinal 
  

   angles. 
  Muscular 
  impression 
  subtriangular 
  or 
  flabelliform, 
  

   extending 
  for 
  two-fifths 
  the 
  length 
  of 
  the 
  shell. 
  A 
  central 
  

   longitudinal 
  callosity 
  extends 
  from 
  the 
  apex, 
  sometimes 
  for 
  

   one-third 
  of 
  the 
  length 
  of 
  the 
  muscular 
  impression. 
  

  

  Dorsal 
  valve 
  very 
  concave, 
  nearly 
  following 
  the 
  contour 
  of 
  

   the 
  ventral 
  valve. 
  Hinge 
  area 
  narrower 
  than 
  that 
  of 
  the 
  ven- 
  

   tral 
  valve 
  ; 
  foramen 
  covered 
  by 
  a 
  callosity. 
  

  

  Surface 
  marked 
  by 
  strong, 
  large, 
  radiating 
  striae, 
  alternating 
  

   with 
  four 
  or 
  five 
  smaller 
  striae 
  and 
  increasing 
  by 
  implantation 
  ; 
  

   radiating 
  striae 
  crossed 
  by 
  very 
  fine, 
  sharp, 
  crowded, 
  regular, 
  

   continuous, 
  crenulating 
  concentric 
  striae 
  ; 
  the 
  small 
  radiating 
  

   striae 
  often 
  become 
  stronger, 
  forming 
  the 
  larger 
  and 
  less 
  regu- 
  

   lar 
  striae 
  ; 
  interior 
  of 
  valves 
  papillose 
  or 
  punctate. 
  

  

  The 
  surface 
  of 
  many 
  of 
  the 
  older 
  specimens 
  is 
  more 
  irregu- 
  

   larly 
  fasciculate, 
  and 
  the 
  stronger 
  striae 
  rise 
  in 
  unequal 
  ridges. 
  

   This 
  latter 
  feature 
  is, 
  in 
  a 
  greater 
  or 
  less 
  degree, 
  impressed 
  

   upon 
  the 
  casts 
  of 
  the 
  interior, 
  which, 
  combined 
  with 
  strong 
  

   vascular 
  markings, 
  gives 
  a 
  distinguishing 
  character 
  to 
  speci- 
  

   mens 
  in 
  that 
  condition. 
  

  

  A 
  fine 
  large 
  specimen 
  in 
  the 
  collections 
  from 
  Waldron 
  shows 
  

   several 
  specific 
  characters 
  not 
  observed 
  in 
  the 
  imperfect 
  mate- 
  

   rial 
  from 
  which 
  the 
  original 
  description 
  was 
  drawn. 
  

  

  Steophodoistta 
  steiata. 
  

  

  Plate 
  23, 
  Figs. 
  1-6. 
  

  

  Strophomena 
  striata 
  Hall,. 
  Geol. 
  of 
  N. 
  Y. 
  Surv. 
  4th 
  Geolog. 
  Dist., 
  p. 
  104, 
  fig. 
  3. 
  

  

  1843. 
  

   Leptaina 
  striata 
  Hall,. 
  Pal. 
  N. 
  Y., 
  vol. 
  ii, 
  p. 
  259, 
  pi. 
  53, 
  fig. 
  7. 
  1852. 
  

  

  This 
  species 
  is 
  of 
  common 
  occurrence 
  in 
  the 
  Waldron 
  local- 
  

   ity 
  and 
  the 
  specimens 
  are 
  usually 
  larger 
  than 
  those 
  of 
  the 
  New 
  

   York 
  fauna. 
  The 
  figures 
  given 
  on 
  plate 
  23, 
  illustrate 
  the 
  inte- 
  

   rior 
  structure 
  which 
  I 
  have 
  not 
  been 
  able 
  to 
  observe 
  in 
  any 
  of 
  

   the 
  specimens 
  from 
  the 
  Niagara 
  formation 
  of 
  New 
  York. 
  In 
  

   the 
  ventral 
  valve, 
  the 
  muscular 
  area 
  is 
  limited 
  by 
  slightly 
  curv- 
  

   ing 
  dental 
  lamellae, 
  and 
  in 
  well-preserved 
  specimens 
  there 
  is 
  a 
  

   slender 
  ridge 
  along 
  the 
  center; 
  the 
  muscular 
  impressions 
  are 
  

  

  