﻿164 
  TWEKTY-EIGHTH 
  KePOBT 
  02* 
  THE 
  STATE 
  MUSEUM. 
  

  

  forward 
  of 
  the 
  umbo 
  ; 
  three 
  or 
  four 
  of 
  the 
  plications 
  continu- 
  

   ing 
  direct, 
  and 
  forming 
  a 
  mesial 
  elevation, 
  the 
  lateral 
  ones 
  

   arching 
  downward 
  to 
  the 
  margin. 
  Shell 
  marked 
  by 
  from 
  nine 
  

   to 
  twelve 
  strong, 
  rounded 
  or 
  subangular 
  plications, 
  which 
  

   sometimes 
  become 
  obsolete 
  toward 
  the 
  beak. 
  The 
  concentric 
  

   lines 
  are 
  very 
  obscure. 
  Length 
  about 
  13 
  mm. 
  

  

  This 
  species 
  resembles 
  the 
  R. 
  neglecta 
  of 
  the 
  Niagara 
  group 
  

   of 
  New 
  York 
  ; 
  but 
  it 
  is 
  larger 
  and 
  more 
  robust, 
  with 
  stronger 
  

   and 
  more 
  rounded 
  plications 
  ; 
  it 
  is 
  associated 
  with 
  a 
  more 
  

   finely 
  plicated 
  species 
  which 
  I 
  have 
  identified 
  with 
  that 
  one. 
  

  

  Rhynchonella 
  Whitii. 
  

  

  Plate 
  26, 
  Figs. 
  23-33. 
  

  

  Rhynchonella 
  Whitii 
  Hall. 
  Trans. 
  Alb. 
  Inst., 
  vol. 
  iv, 
  p. 
  216. 
  Abstract, 
  p. 
  22; 
  

   May, 
  1863. 
  

  

  Shell 
  sub 
  circular 
  or 
  transverse 
  and 
  broadly 
  elliptical, 
  

   usually 
  not 
  very 
  gibbous. 
  Ventral 
  valve 
  shallow, 
  most 
  promi- 
  

   nent 
  on 
  the 
  umbo, 
  beak 
  abruptly 
  attenuate 
  and 
  pointed, 
  

   slightly 
  incurved, 
  sides 
  flattened, 
  strongly 
  sinuate 
  in 
  the 
  mid- 
  

   dle 
  and 
  gently 
  curving 
  upward 
  in 
  front. 
  Dorsal 
  valve 
  more 
  

   gibbous; 
  beak 
  obtuse 
  and 
  incurved 
  beneath 
  the 
  opposite, 
  

   elevated 
  in 
  the 
  middle, 
  forming 
  a 
  distinct 
  mesial 
  fold, 
  arching 
  

   on 
  the 
  sides 
  ; 
  from 
  five 
  to 
  six 
  strong 
  plications 
  on 
  each 
  side 
  of 
  

   the 
  mesial 
  fold 
  and 
  sinus, 
  with 
  usually 
  a 
  single 
  plication 
  in 
  

   the 
  sinus, 
  and 
  two 
  on 
  the 
  mesial 
  fold 
  ; 
  rarely 
  one 
  of 
  the 
  plica- 
  

   tions 
  on 
  the 
  fold 
  is 
  bifurcate. 
  Interspaces 
  wider 
  than 
  the 
  plica- 
  

   cations. 
  Surface 
  marked 
  by 
  close 
  concentric 
  lines 
  of 
  growth. 
  

  

  This 
  species 
  bears 
  some 
  resemblance 
  to 
  R. 
  (Atrypa) 
  den- 
  

   tata 
  (Pal. 
  N. 
  Y., 
  vol. 
  i, 
  p. 
  148), 
  but 
  is 
  less 
  gibbous, 
  the 
  pli- 
  

   cations 
  less 
  strong, 
  the 
  mesial 
  fold 
  less 
  elevated, 
  and 
  the 
  

   sinus 
  much 
  narrower. 
  It 
  also 
  is 
  related 
  to 
  R. 
  borealis 
  

   Schloth. 
  (Davidson's 
  British 
  Fossil 
  Brachiopoda, 
  No. 
  iii, 
  Pt. 
  

   vii, 
  p. 
  174, 
  PI. 
  xxi, 
  figs. 
  14-23), 
  and 
  is 
  distinguished 
  by 
  its 
  

   smaller 
  and 
  rounded 
  form, 
  less 
  prominent 
  plications, 
  and 
  

   by 
  its 
  surface-markings. 
  

  

  