﻿850 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  appears 
  to 
  be 
  due 
  to 
  variation 
  in 
  the 
  rate 
  of 
  their 
  multipli- 
  

   cation. 
  In 
  the 
  umbonal 
  regions 
  the 
  plications 
  are 
  obsolete. 
  

   Magara 
  dolomites. 
  If 
  ear 
  Milwaukee, 
  Wisconsin. 
  

  

  Conchidium 
  crassiplica, 
  sp. 
  nov. 
  

   (Plate 
  lxvi, 
  figs. 
  24, 
  25.) 
  

  

  Shell 
  elongate, 
  subelliptical 
  in 
  outline. 
  Valves 
  subequally 
  con- 
  

   vex, 
  depressed 
  above 
  ; 
  cardinal 
  slopes 
  broad 
  and 
  abrupt 
  on 
  both. 
  

   Umbo 
  of 
  the 
  pedicle-valve 
  erect, 
  not 
  prominent 
  ; 
  surface 
  slightly 
  

   elevated 
  medially. 
  Umbo 
  of 
  brachial 
  valve 
  depressed, 
  apex 
  con- 
  

   cealed; 
  median 
  region 
  depressed 
  anteriorly; 
  surface 
  of 
  both 
  

   valves 
  bearing 
  broad 
  rounded 
  plications, 
  separated 
  by 
  deep 
  

   grooves. 
  Of 
  these 
  plications 
  there 
  are 
  from 
  eight 
  to 
  ten 
  on 
  each 
  

   valve 
  over 
  the 
  pallial 
  region 
  ; 
  by 
  dichotomizing 
  these 
  become 
  

   more 
  numerous 
  anteriorly. 
  

  

  Niagara 
  group. 
  Near 
  Louisville, 
  Kentucky. 
  

  

  Conchidium 
  Georgiae, 
  sp. 
  nov. 
  

  

  (Plate 
  lxvi, 
  figs. 
  18, 
  19.) 
  

  

  Pedicle-valve 
  unknown 
  ; 
  brachial-valve 
  trilobed 
  by 
  the 
  develop- 
  

   ment 
  of 
  a 
  strong 
  median 
  fold 
  which 
  extends 
  from 
  apex 
  to 
  margin, 
  

   and 
  is 
  sharply 
  delimited 
  by 
  abrupt 
  lateral 
  slopes. 
  The 
  sides 
  of 
  

   the 
  valve 
  are 
  convex, 
  rather 
  narrow, 
  and 
  slope 
  abruptly 
  to 
  the 
  

   lateral 
  margins. 
  Umbo 
  full 
  and 
  incurved. 
  Surface 
  covered 
  with 
  

   numerous 
  duplicating 
  plications, 
  of 
  which 
  from 
  fifteen 
  to 
  twenty 
  

   may 
  be 
  counted 
  on 
  each 
  side 
  at 
  the 
  margins, 
  and 
  twelve 
  to 
  

   fourteen 
  in 
  the 
  fold. 
  

  

  Clinton 
  group. 
  Trenton, 
  Georgia. 
  

  

  Capellinia 
  mira, 
  sp. 
  nov. 
  

  

  (Plate 
  lxx, 
  figs. 
  7-14.) 
  

  

  (See 
  pages 
  248, 
  249.) 
  

  

  Selenella 
  gracilis, 
  sp. 
  nov. 
  

  

  (See 
  page 
  270, 
  figs. 
  184-186.) 
  

  

  Oriskania 
  navicella, 
  sp. 
  nov. 
  

  

  (Plate 
  lxxix, 
  figs. 
  25-27.) 
  

   (See 
  pages 
  269, 
  270, 
  figs. 
  181-183.) 
  

  

  