﻿Report 
  of 
  the 
  State 
  Geologist. 
  1015 
  

  

  on 
  the 
  opposite 
  valve 
  subserving 
  to 
  some 
  extent 
  purposes 
  of 
  

   articulation. 
  Spirals 
  duplicate 
  and 
  echinate; 
  spiral 
  cones 
  

   depressed. 
  

  

  ^„ 
  

  

  Figs. 
  410, 
  411.— 
  Koninckodonta 
  Fuggeri, 
  Bittner. 
  (Bittxer.) 
  

  

  Type,^ 
  Koninckodonta 
  Fuggeri, 
  Bittner. 
  

   Distribution. 
  Triassic. 
  

  

  Thecospira, 
  Zugmayer. 
  1880. 
  

  

  Shells" 
  small, 
  concavo-convex, 
  attached 
  by 
  the 
  umbo 
  of 
  the 
  

   pedicle-valve. 
  Surface 
  smooth 
  or 
  concentrically 
  rugose 
  ; 
  covered 
  

   with 
  a 
  tubercled 
  periostracum. 
  Shell 
  substance 
  perforate. 
  

   Cardinal 
  area 
  and 
  deltarium 
  well-developed. 
  In 
  the 
  pedicle- 
  

   valve 
  the 
  teeth] 
  are 
  conspicuous 
  and 
  unsupported 
  ; 
  a 
  median 
  

   septum 
  divides 
  the 
  deeply 
  impressed 
  muscular 
  scars. 
  In 
  the 
  

   brachial 
  valve 
  the 
  cardinal 
  process 
  is 
  large, 
  elevated, 
  tripartite 
  on 
  

   the 
  summit, 
  deeply 
  grooved 
  in 
  the 
  middle. 
  Spiral 
  cones 
  double, 
  

   directed 
  toward 
  the 
  lateral 
  slopes 
  of 
  the 
  pedicle-valve. 
  The 
  

  

  <&m 
  

  

  Figs. 
  412, 
  413.— 
  Thecospira 
  Haidingei 
  i, 
  Suess 
  (sp.). 
  (Zugmayer.) 
  

  

  jugum 
  is 
  a 
  simple 
  arch, 
  broadened 
  at 
  its 
  summit 
  and 
  con- 
  

   tinued 
  into 
  intercalary 
  lamellae 
  which 
  are 
  coextensive 
  with 
  

   the 
  principal 
  coils. 
  The 
  iatter 
  are 
  fimbriated 
  on 
  their 
  outer 
  

   margins. 
  

  

  Type, 
  Thecospira 
  Haidingeri, 
  Suess 
  (sp.). 
  

  

  Distribution. 
  Triassic. 
  

  

  73 
  

  

  