﻿368 
  Forty- 
  seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  situated 
  at 
  the 
  anterior 
  one-fifth, 
  of 
  the 
  transverse 
  diameter. 
  The 
  

   anterior 
  margin 
  is 
  narrowly 
  convex, 
  rounding 
  abruptly 
  to 
  the 
  

   ventral 
  margin 
  which 
  is 
  broadly 
  curved 
  to 
  the 
  subacute 
  posterior 
  

   extremity. 
  On 
  the 
  posterior 
  margin 
  the 
  slope 
  is 
  obliquely 
  forward, 
  

   and 
  a 
  large 
  angle 
  is 
  formed 
  at 
  the 
  union 
  of 
  the 
  posterior 
  and 
  

   dorsal 
  margins. 
  The 
  umbones 
  are 
  broadly 
  flattened, 
  and 
  this 
  

   flattened 
  area 
  widens 
  over 
  the 
  pallial 
  region 
  of 
  the 
  valves. 
  Pos- 
  

   teriorly 
  it 
  is 
  sharply 
  delimited 
  by 
  the 
  umbonal 
  ridge, 
  from 
  which 
  

   the 
  slope 
  is 
  slightly 
  concave 
  to 
  the 
  posterior 
  margin. 
  A 
  well- 
  

   defined 
  clavicular 
  ridge 
  extends 
  from 
  the 
  anterior 
  edge 
  of 
  the 
  

   beak 
  with 
  a 
  slight 
  inward 
  curve, 
  two-thirds 
  of 
  the 
  distance 
  to 
  the 
  

   ventral 
  margin. 
  Surface 
  covered 
  with 
  fine 
  concentric 
  striae. 
  

   Length 
  of 
  average 
  specimens, 
  20 
  mm.; 
  height, 
  13 
  mm.; 
  greatest 
  

   transverse 
  diameter, 
  21 
  mm. 
  

  

  This 
  shell 
  is 
  intermediate 
  in 
  its 
  contour 
  and 
  outline 
  between 
  

   the 
  elongate, 
  posteriorly 
  acuminate 
  JV. 
  cuneiformis, 
  Conrad, 
  and 
  

   the 
  shorter 
  more 
  sharply 
  angled 
  N. 
  triqueter, 
  Conrad. 
  It 
  is, 
  how- 
  

   ever, 
  persistent 
  in 
  the 
  features 
  described, 
  and 
  is 
  not 
  of 
  infrequent 
  

   occurrence 
  in 
  the 
  Hamilton 
  shales 
  at 
  from 
  447 
  to 
  463 
  feet 
  in 
  the 
  

   Shaft. 
  The 
  specimens 
  figured 
  are 
  from 
  at 
  depth 
  of 
  450 
  feet. 
  

  

  Lucina(?) 
  Livonensis, 
  sp. 
  nov. 
  

   Plate 
  IV, 
  fig. 
  1, 
  

  

  This 
  is 
  a 
  rather 
  small, 
  subcircular 
  shell 
  which 
  has 
  the 
  outline 
  

   and 
  essentially 
  the 
  external 
  expression 
  of 
  the 
  common 
  species 
  in 
  

   the 
  Naples 
  shales 
  described 
  originally 
  as 
  Ungulina 
  suborbicularis, 
  

   but 
  which 
  has 
  been 
  variously 
  referred 
  since, 
  while 
  its 
  generic 
  

   characters 
  still 
  await 
  elucidation. 
  Such 
  forms, 
  however, 
  have 
  

   been 
  so 
  rarely, 
  if 
  ever, 
  observed 
  in 
  faunas 
  antedating 
  the 
  extinc- 
  

   tion 
  of 
  the 
  normal 
  fauna 
  of 
  the 
  Hamilton 
  shales 
  that 
  the 
  occur- 
  

   rence 
  of 
  one 
  in 
  the 
  Marcellus 
  shales 
  (at 
  a 
  depth 
  in 
  the 
  Shaft 
  of 
  

   820 
  feet) 
  prompts 
  a 
  notice 
  of 
  it. 
  

  

  The 
  beak 
  is 
  scarcely 
  prominent, 
  is 
  situated 
  in 
  front 
  of 
  the 
  

   middle 
  of 
  the 
  valve, 
  hence 
  the 
  posterior 
  dorsal 
  slope 
  is 
  longer 
  

   than 
  the 
  anterior. 
  The 
  surface 
  is 
  evenly 
  convex 
  and 
  is 
  smooth 
  

   though 
  bearing 
  low, 
  concentric 
  wrinkles, 
  which 
  are 
  most 
  promi- 
  

   nent 
  about 
  the 
  umbo. 
  These 
  are 
  crossed 
  by 
  faint, 
  distant 
  incised 
  

   radiating 
  striae. 
  

  

  