﻿1092 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  which 
  is 
  somewhat 
  incurved 
  over 
  the 
  broad, 
  arched 
  cardinal 
  area. 
  

   Deltidium 
  conspicuously 
  developed. 
  Interior 
  of 
  both 
  valves 
  with 
  

   broad, 
  thickened 
  granulose 
  marginal 
  areas. 
  In 
  the 
  pedicle-valve 
  

   the 
  teeth 
  are 
  small 
  and 
  parallel 
  ; 
  the 
  adductor 
  muscles 
  rest 
  upon 
  

   a 
  short 
  median 
  plate 
  lying 
  directly 
  in 
  front 
  of 
  the 
  deltidium, 
  at 
  

   each 
  side 
  of 
  which 
  is 
  the 
  transversely 
  oval 
  scar 
  of 
  the 
  diductors. 
  

   Yisceral 
  area 
  large, 
  smooth 
  and 
  divided 
  medially 
  by 
  a 
  granulated 
  

  

  Figs. 
  613, 
  644. 
  Thecidea 
  radiata, 
  o, 
  deltidium; 
  fcfc, 
  teeth; 
  ab, 
  adductors, 
  e, 
  diductors; 
  h, 
  car- 
  

   dinal 
  process; 
  i, 
  cardinal 
  plate; 
  g, 
  brachial 
  supports. 
  (Sukss.) 
  

  

  ridge. 
  In 
  the 
  brachial 
  valve 
  the 
  cardinal 
  process 
  is 
  large, 
  erect 
  

   and 
  subtriangular. 
  The 
  median 
  septum 
  branches 
  repeatedly 
  

   from 
  its 
  posterior 
  extremity 
  forward, 
  and 
  this 
  forms 
  a 
  series 
  of 
  

   depressions 
  or 
  grooves 
  of 
  unequal 
  length 
  in 
  which 
  lay 
  the 
  lobes 
  

   of 
  the 
  brachia. 
  

  

  Type, 
  Thecidea 
  papillata, 
  Schlotheim 
  (sp.). 
  

  

  Distribution. 
  Cretaceous. 
  

  

  Subgenus 
  Lacazella, 
  Munier-Chalmas. 
  1880. 
  

  

  Shells 
  subtrigona], 
  solidly 
  attached 
  by 
  the 
  apex 
  of 
  the 
  pedicle 
  

   valve 
  ; 
  surface 
  smooth 
  or 
  with 
  concentric 
  growth 
  lines. 
  Pedicle- 
  

   valve 
  with 
  conspicuous 
  cardinal 
  area 
  and 
  deltidium; 
  muscular 
  

   plate 
  concave, 
  small, 
  free 
  at 
  its 
  anterior 
  extremity. 
  In 
  the 
  

   brachial 
  valve 
  the 
  cardinal 
  process 
  is 
  strong, 
  subrectangular, 
  

   concave 
  toward 
  the 
  base, 
  and 
  projected 
  beyond 
  the 
  hinge. 
  The 
  

   cavities 
  of 
  the 
  brachial 
  lobes 
  in 
  two 
  or 
  three 
  unequal 
  pairs. 
  

  

  Animal 
  with 
  short 
  alimentary 
  canal 
  ; 
  embryos 
  developed 
  in 
  a 
  

   pouch 
  or 
  marsupium 
  situated 
  at 
  the 
  bottom 
  of 
  the 
  pedicle-valve, 
  

   and 
  attached 
  to 
  the 
  brachia 
  by 
  a 
  pair 
  of 
  long 
  cilia. 
  

  

  150 
  

  

  