﻿Report 
  of 
  the 
  State 
  Geologist. 
  1041 
  

  

  valve. 
  The 
  character 
  of 
  this 
  structure 
  in 
  the 
  brachial 
  valve 
  

   is 
  not 
  variable 
  in 
  this 
  genus. 
  

  

  Type, 
  Gypidula 
  comis, 
  Owen 
  (sp.). 
  

  

  Distribution. 
  Devonian. 
  

  

  Capellinia, 
  Hall. 
  1893. 
  

   (Plate 
  47, 
  figs. 
  10-12.) 
  

  

  Shells 
  large, 
  elongate- 
  subovate 
  ; 
  the 
  relative 
  size 
  and 
  convexity 
  

   of 
  the 
  valves, 
  normal 
  for 
  Pentamerus, 
  are 
  here 
  reversed, 
  the 
  

   brachial 
  valve 
  being 
  the 
  larger 
  and 
  deeper, 
  with 
  full, 
  strongly 
  

   arcuate 
  and 
  incurved 
  umbo 
  and 
  beak, 
  the 
  apex 
  of 
  which 
  is 
  con- 
  

   cealed 
  within 
  the 
  delthyrium 
  of 
  the 
  opposite 
  valve. 
  The 
  

   pedicle-valve 
  has 
  an 
  acute 
  suberect 
  beak 
  which 
  is 
  not 
  arched 
  pos- 
  

   teriorly, 
  but 
  rises 
  directly 
  from 
  the 
  cardinal 
  margins. 
  Below 
  it 
  

   is 
  a 
  broad 
  delthyrium 
  without 
  evidence 
  of 
  deltidial 
  plates 
  ; 
  there 
  

   is 
  no 
  hinge-line, 
  but 
  the 
  margins 
  of 
  the 
  delthyrium 
  make 
  sub- 
  

   acute 
  angles 
  with 
  the 
  lateral 
  margins 
  of 
  the 
  valve. 
  Cardinal 
  

   slopes 
  very 
  broad 
  and 
  abrupt. 
  The 
  surface 
  of 
  the 
  pedicle-valve 
  

   is 
  flattened 
  above, 
  while 
  that 
  of 
  the 
  brachial 
  valve 
  is 
  evenly 
  and 
  

   deeply 
  convex 
  ; 
  it 
  also 
  shows 
  a 
  tendency 
  to 
  trilobation 
  or 
  obscure 
  

   radical 
  plication. 
  The 
  arrangement 
  of 
  the 
  internal 
  septa 
  and 
  

   spondylium 
  is 
  the 
  same 
  as 
  in 
  Pentamerus 
  oblongus, 
  except 
  that 
  

   the 
  supporting 
  septa 
  of 
  the 
  brachial 
  valve 
  are 
  higher 
  and 
  more 
  

   nearly 
  vertical. 
  

  

  Type, 
  Capellinia 
  mira, 
  Hall. 
  

  

  Distribution. 
  Upper 
  Silurian. 
  

  

  Stricklandinia, 
  Billings. 
  (1863), 
  1859. 
  

   (Plate 
  49, 
  figs. 
  1-7.) 
  

  

  Shells 
  usually 
  large, 
  elongate-oval, 
  transversely-oval 
  or 
  circular 
  ; 
  

   in 
  some 
  species 
  with 
  a 
  straight 
  hinge-line, 
  more 
  or 
  less 
  extended. 
  

   Valves 
  nearly 
  equal, 
  varying 
  from 
  depressed 
  convex 
  to 
  strongly 
  

   convex. 
  In 
  the 
  interior 
  of 
  the 
  pedicle-valve 
  is 
  a 
  short 
  median 
  

   septum 
  supporting 
  a 
  small, 
  triangular 
  chamber 
  beneath 
  the 
  beak. 
  

   In 
  the 
  brachial 
  valve 
  are 
  two 
  very 
  short 
  or 
  rudimentary 
  socket 
  

   plates, 
  which 
  in 
  some 
  species 
  bear 
  prolonged 
  crura. 
  Both 
  valves 
  

   with 
  distinct 
  cardinal 
  area, 
  that 
  of 
  the 
  pedicle-valve 
  the 
  larger, 
  

   the 
  dorsal 
  area 
  sometimes 
  incurved 
  over 
  the 
  ventral, 
  and 
  con- 
  

   cealing 
  it 
  wholly 
  or 
  in 
  part. 
  

  

  13 
  L 
  99 
  

  

  