﻿842 
  Forty- 
  seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

   Plectambonites 
  producta, 
  sp. 
  nov. 
  

  

  (Plate 
  lxxxiv, 
  figs. 
  23-25.) 
  

  

  The 
  original 
  of 
  this 
  species 
  is 
  an 
  internal 
  cast 
  of 
  the 
  pedicle- 
  

   valve, 
  with 
  short, 
  straight 
  hinge, 
  rather 
  narrow, 
  depressed 
  umbo, 
  

   the 
  shell 
  becoming 
  highly 
  convex 
  and 
  greatly 
  produced 
  ante- 
  

   riorly. 
  The 
  sides 
  of 
  the 
  valve 
  are 
  somewhat 
  appressed 
  medially 
  

   and 
  the 
  anterior 
  margin 
  slightly 
  expanded, 
  and 
  suboval 
  in 
  outline. 
  

   The 
  cast 
  shows 
  the 
  impression 
  of 
  short 
  divergent 
  dental 
  plates 
  

   and 
  a 
  moderately 
  broad 
  muscular 
  impression. 
  The 
  width 
  of 
  the 
  

   shell 
  on 
  the 
  hinge 
  is 
  10 
  mm. 
  ; 
  its 
  length, 
  23 
  mm.; 
  its 
  convexity 
  

   from 
  the 
  posterior 
  margin, 
  8 
  mm.; 
  from 
  the 
  anterior 
  margin, 
  

   28 
  mm. 
  

  

  Niagara 
  dolomites. 
  Yellow 
  Springs, 
  Ohio. 
  

  

  Spirifer 
  crispatus, 
  sp. 
  nov. 
  

  

  (Plate 
  xxxvi, 
  figs. 
  9, 
  10.) 
  

  

  Shell 
  small, 
  with 
  moderately 
  high, 
  incurved 
  area, 
  scarcely 
  

   extended 
  on 
  the 
  hinge, 
  well-developed 
  median 
  fold 
  and 
  sinus, 
  

   and 
  three 
  coarse 
  plications 
  on 
  each 
  lateral 
  slope. 
  The 
  surface 
  is 
  

   covered 
  by 
  conspicuous 
  concentric 
  lamellae. 
  

  

  Magara 
  group. 
  Maryland. 
  

  

  Spirifer 
  Canandaiguae, 
  sp. 
  nov. 
  

  

  (Plate 
  xxxvii, 
  figs. 
  23, 
  24, 
  25.) 
  

  

  Shells 
  of 
  rather 
  small 
  size, 
  having 
  somewhat 
  the 
  aspect 
  of 
  an 
  

   elongate 
  and 
  umbonate 
  S. 
  fimbriatus. 
  Umbo 
  of 
  pedicle-valve 
  

   prominent, 
  narrow 
  and 
  closely 
  incurved 
  at 
  the 
  apex. 
  Hinge-line 
  

   quite 
  short, 
  cardinal 
  small, 
  incurved. 
  Median 
  sinus 
  deep, 
  pro- 
  

   duced 
  on 
  the 
  anterior 
  margin, 
  its 
  anterior 
  width 
  being 
  nearly 
  

   equal 
  to 
  the 
  length 
  of 
  the 
  hinge. 
  On 
  each 
  lateral 
  slope 
  are 
  from 
  

   two 
  to 
  four 
  low 
  radial 
  undulations 
  or 
  plications, 
  all 
  of 
  which 
  are 
  

   sharply 
  defined 
  at 
  the 
  umbones. 
  Surface 
  covered 
  with 
  very 
  fine, 
  

   closely 
  crowded 
  concentric 
  lines 
  which 
  are 
  granulous 
  and 
  were 
  

   originally 
  fimbriate. 
  Length 
  of 
  typical 
  specimen, 
  21 
  mm. 
  ; 
  great- 
  

   est 
  width, 
  22 
  mm. 
  ; 
  length 
  of 
  hinge, 
  10 
  mm. 
  

  

  Hamilton 
  group. 
  Centerfield 
  and 
  Canandaigua 
  Lake, 
  N. 
  Y. 
  

  

  