﻿Report 
  of 
  the 
  State 
  Geologist. 
  

  

  1013 
  

  

  Karpinskia, 
  Tschernyschew. 
  1885. 
  

   (Plate 
  41, 
  figs. 
  18-20.) 
  

  

  Atrypoid 
  shells 
  with 
  elongate 
  form, 
  radially 
  plicated 
  and 
  sub- 
  

   equally 
  convex 
  valves. 
  The 
  spirals 
  have 
  the 
  same 
  positions 
  as 
  in 
  

   Atrypa, 
  though 
  the 
  character 
  of 
  the 
  jugum 
  is 
  still 
  unknown. 
  In 
  

   the 
  pedicle- 
  valve 
  are 
  diverging 
  dental 
  plates, 
  and 
  in 
  the 
  brachial 
  

   valve 
  a 
  median 
  septum. 
  The 
  vascular 
  trunks 
  are 
  simple 
  and 
  

   direct, 
  extending 
  to 
  the 
  anterior 
  margin 
  of 
  the 
  valves 
  without 
  

   branching. 
  

  

  Type, 
  Karpinskia 
  conjugula, 
  Tschernyschew. 
  Lower 
  De- 
  

   vonian. 
  

  

  Koninckina, 
  Suess. 
  1852. 
  

  

  Shell 
  suborbic 
  alar, 
  concavo-convex, 
  smooth. 
  Hinge-line 
  straight. 
  

   Apex 
  of 
  pedicle-valve 
  incurved, 
  beak 
  full. 
  Cardinal 
  area 
  and 
  

   deltidial 
  plates 
  obsolete 
  at 
  maturity. 
  Spirals 
  double, 
  the 
  prin- 
  

   cipal 
  pair 
  arising 
  from 
  simple 
  crural 
  processes 
  with 
  the 
  extremi- 
  

   ties 
  of 
  which 
  they 
  made 
  a 
  sharp 
  angle. 
  The 
  jugum 
  is 
  formed 
  

  

  Figs. 
  402, 
  403. 
  Koninckina 
  ; 
  reconstruction 
  of 
  the 
  brachial 
  apparatus. 
  (Bittner.) 
  

  

  by 
  the 
  anterior 
  extension 
  and 
  union 
  of 
  the 
  ' 
  crural 
  ^processes. 
  

   The 
  accessory 
  spirals 
  are 
  coextensive 
  with 
  the 
  main 
  pair 
  

   and 
  take 
  their 
  origin 
  from 
  the 
  upper 
  surface 
  of 
  the 
  jugum. 
  

   The 
  spiral 
  cones 
  are 
  depressed 
  and 
  have 
  their 
  apices 
  directed 
  

   toward 
  the 
  lateral 
  slopes 
  of 
  the 
  pedicle-valve. 
  

  

  Type, 
  Koninckina 
  Zeonhardi, 
  Wissman 
  (sp.). 
  

  

  Distribution. 
  Triassic. 
  

  

  71 
  

  

  