﻿1062 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  thinner 
  and 
  higher 
  towards 
  the 
  front, 
  ending 
  abruptly 
  in 
  the 
  

   pallial 
  region. 
  

  

  In 
  the 
  brachial 
  valvefthe 
  umbo 
  is 
  obtuse. 
  The 
  cardinal 
  area 
  

   is 
  distinctly 
  developed 
  and 
  divided 
  by 
  a 
  very 
  broad 
  triangular 
  

   fissure, 
  the 
  covering 
  of 
  which 
  (chilidium) 
  is 
  frequently 
  retained, 
  

   much 
  modified 
  by 
  the 
  presence 
  of 
  the 
  great 
  cardinal 
  process. 
  

   The 
  dental 
  sockets 
  are 
  comparatively 
  shallow. 
  The 
  general 
  form 
  

   of 
  the 
  hinge-plate 
  is 
  triangular, 
  with 
  its 
  apex 
  anterior 
  ; 
  its 
  central 
  

   portion 
  is 
  separated 
  from 
  the 
  narrow, 
  blade-shaped 
  lateral 
  

   divisions 
  and 
  js 
  produced 
  into 
  a 
  great 
  cardinal 
  process, 
  rounded 
  

  

  Fig. 
  509. 
  Stringocephalus 
  Burtini, 
  Defrance. 
  

  

  Dorsal 
  views 
  of 
  two 
  individuals; 
  showing 
  the 
  differences 
  assumed 
  in 
  growth 
  by 
  the 
  umbo 
  of 
  

   the 
  pedicle-valve. 
  (Quknstedt.) 
  

  

  posteriorly, 
  narrow 
  and 
  sharp 
  on 
  its 
  anterior 
  surface, 
  and 
  pro- 
  

   duced 
  upward 
  and 
  backward 
  into 
  the 
  cavity 
  of 
  the 
  opposite 
  

   valve. 
  At 
  the 
  edge 
  of 
  the 
  median 
  septum 
  of 
  that 
  valve 
  it 
  bifur- 
  

   cates, 
  sending 
  out 
  a 
  short 
  clavate 
  apophysis 
  on 
  either 
  side 
  of 
  it. 
  

   The 
  lateral 
  portions 
  of 
  the 
  hinge-plate 
  begin 
  at 
  the 
  socket- 
  walls 
  

   which 
  are 
  high 
  and 
  narrow, 
  extend 
  downward, 
  inward 
  and 
  for- 
  

   ward 
  to 
  the 
  anterior 
  extremity 
  of 
  the 
  plate, 
  whence 
  they 
  curve 
  

   upward 
  into 
  the 
  crura. 
  The 
  crura 
  are 
  long, 
  broadened 
  and 
  

   curved 
  upward 
  towards 
  their 
  extremities 
  where 
  the 
  primary 
  arms 
  

   of 
  the 
  brachidium 
  arise 
  at 
  a 
  sharp 
  angle. 
  The 
  latter 
  curve 
  

   backward 
  and 
  outward, 
  and 
  skirt 
  the 
  inner 
  margins 
  of 
  the 
  valves 
  

  

  120 
  

  

  