﻿Report 
  of 
  the 
  State 
  Geologist. 
  847 
  

  

  Zygospira 
  putilla, 
  sp. 
  nov. 
  

   (Plate 
  liv, 
  figs. 
  35-37.) 
  

  

  Shell 
  small, 
  elongate 
  suboval 
  in 
  outline. 
  Pedicle-valve 
  the 
  

   more 
  convex; 
  umbo 
  narrowed, 
  apex 
  acute, 
  delthyrium 
  inclosed. 
  

   Medially 
  this 
  valve 
  is 
  elevated 
  by 
  a 
  strong 
  double 
  plication, 
  the 
  

   parts 
  of 
  which 
  diverge 
  anteriorly, 
  leaving 
  a 
  flat 
  low 
  depression 
  

   between 
  them, 
  and 
  in 
  this 
  lies 
  a 
  single 
  faint 
  plication. 
  The 
  

   lateral 
  slopes 
  are 
  considerably 
  depressed, 
  and 
  each 
  bears 
  from 
  

   four 
  to 
  seven, 
  coarse, 
  often 
  irregular 
  plications, 
  only 
  a 
  part 
  of 
  

   them 
  reaching 
  the 
  beak. 
  

  

  The 
  brachial 
  valve 
  is 
  depressed 
  convex, 
  with 
  a 
  conspicuous 
  

   median 
  fold, 
  grooved 
  longitudiually 
  and 
  bounded 
  by 
  deep 
  

   marginal 
  depressions. 
  The 
  lateral 
  slopes 
  are 
  more 
  convex 
  than 
  on 
  

   the 
  other 
  valve, 
  but 
  are 
  similarly 
  plicated. 
  

  

  Surface 
  of 
  the 
  valves 
  usually 
  without 
  concentric 
  growth 
  lines. 
  

  

  An 
  average 
  example 
  has 
  a 
  length 
  of 
  8 
  mm. 
  and 
  a 
  greatest 
  width 
  

   of 
  7 
  mm. 
  

  

  Hudson 
  River 
  group. 
  JVear 
  Edgewood, 
  Pike 
  county 
  ', 
  Missouri. 
  

  

  Camarophoria 
  rhomboidalis, 
  sp. 
  nov. 
  

   (Plate 
  lxii, 
  figs. 
  25-29.) 
  

  

  Shells 
  of 
  rather 
  small 
  size, 
  subtriangular 
  in 
  outline 
  with 
  cardinal 
  

   margins 
  extending 
  for 
  half 
  the 
  length 
  of 
  the 
  valves. 
  Pedicle- 
  

   valve 
  with 
  apex 
  scarcely 
  elevated, 
  incurved, 
  with 
  deltidial 
  plates 
  

   usually 
  concealed 
  ; 
  slightly 
  convex 
  about 
  the 
  umbo, 
  broadly 
  

   depressed 
  medially, 
  forming 
  a 
  sinus 
  which 
  makes 
  a 
  linguiform 
  

   extension 
  on 
  the 
  anterior 
  margin. 
  This 
  sinus 
  may 
  bear 
  one 
  and 
  

   sometimes 
  traces 
  of 
  two 
  other 
  low 
  plications. 
  The 
  lateral 
  slopes 
  

   are 
  smooth, 
  except 
  at 
  the 
  margins, 
  where 
  there 
  is 
  faint 
  evidence 
  

   of 
  one 
  or 
  two 
  plications 
  on 
  each. 
  The 
  brachial 
  valve 
  is 
  convex 
  

   and 
  broadly 
  rounded 
  with 
  abrupt 
  umbo-lateral 
  slopes, 
  broad, 
  low 
  

   median 
  fold, 
  apparent 
  on]y 
  in 
  the 
  pallial 
  region, 
  and 
  bearing 
  a 
  

   median 
  plication. 
  Traces 
  of 
  two 
  lateral 
  plications 
  are 
  visible 
  at 
  

   the 
  margin 
  of 
  the 
  valve, 
  and 
  these 
  are 
  somewhat 
  more 
  distinct 
  

   on 
  the 
  surface 
  than 
  on 
  the 
  opposite 
  valve. 
  Surface 
  smooth 
  or 
  

   with 
  fine 
  concentric 
  lines. 
  The 
  interior 
  structure 
  of 
  the 
  shell 
  is 
  

   normal 
  for 
  this 
  genus. 
  

  

  Corniferous 
  limestone. 
  Ca&s 
  county, 
  Indiana. 
  

  

  