﻿Report 
  of 
  the 
  State 
  Geologist, 
  

  

  987 
  

  

  a 
  well-defined 
  median 
  septum. 
  The 
  spiral 
  ribbon 
  makes 
  but 
  

  

  few 
  (four 
  or 
  five) 
  volutions; 
  the 
  jugum 
  takes 
  its 
  origin 
  behind 
  

   the 
  middle 
  of 
  the 
  primary 
  lamellae, 
  its 
  lateral 
  branches 
  being 
  

   slightly 
  constricted 
  near 
  their 
  bases 
  ; 
  it 
  is 
  inclined 
  backward 
  in 
  a 
  

   broad 
  curve, 
  the 
  union 
  of 
  the 
  lateral 
  branches 
  taking 
  place 
  at 
  a 
  

   point 
  just 
  within 
  the 
  opposite 
  side 
  of 
  the 
  base 
  of 
  the 
  cones. 
  

   From 
  this 
  point 
  the 
  stem 
  of 
  the 
  jugum 
  is 
  continued 
  as 
  a 
  simple 
  

   process, 
  outward 
  between 
  the 
  coils 
  and 
  almost 
  to 
  the 
  inner 
  sur- 
  

   face 
  of 
  the 
  pedicle- 
  valve. 
  

  

  Type, 
  Ptychosjpira 
  ferita, 
  von 
  Buch 
  (sp). 
  Middle 
  Devonian. 
  

  

  Distribution. 
  Devonian 
  — 
  Lower 
  Carboniferous. 
  

  

  Uncites, 
  Defrance. 
  1827. 
  

   (Plate 
  36, 
  figs. 
  24-27.) 
  

   Shells 
  usually 
  of 
  large 
  size, 
  elongate-oval 
  or 
  subtriangular 
  

   in 
  marginal 
  outline 
  ; 
  valves 
  convex. 
  The 
  pedicle-valve 
  has 
  a 
  

   long 
  and 
  acuminate 
  beak 
  which 
  is 
  frequently 
  distorted 
  and 
  

   always 
  arched 
  or 
  incurved. 
  There 
  is 
  no 
  cardinal 
  area 
  and 
  the 
  

   hinge-line 
  is 
  greatly 
  curved. 
  There 
  is 
  no 
  foramen 
  in 
  mature 
  

   individuals 
  though 
  it 
  may 
  be 
  retained 
  in 
  young 
  forms. 
  The 
  

   deltarium 
  is 
  concave 
  and 
  consists 
  of 
  a 
  single 
  piece, 
  all 
  trace 
  of 
  the 
  

   original 
  components 
  being 
  lost. 
  The 
  teeth 
  are 
  supported 
  by 
  

   dental 
  plates 
  and 
  between 
  them 
  lies 
  a 
  broad 
  median 
  ridge 
  which 
  

   narrows 
  as 
  it 
  approaches 
  the 
  hinge. 
  The 
  brachial 
  valve 
  has 
  a 
  

   broad, 
  full 
  beak, 
  which 
  is 
  closely 
  

   incurved 
  and 
  concealed 
  beneath 
  tiie 
  

   deltarium 
  of 
  the 
  opposite 
  valve. 
  The 
  

   cardinal 
  process 
  is 
  large, 
  erect 
  and 
  

   slightly 
  bilobed 
  on 
  its 
  posterior 
  margin 
  ; 
  

   it 
  rests 
  up 
  n 
  a 
  short 
  plate 
  bearing 
  two 
  

   ridges 
  which 
  are 
  continued 
  into 
  the 
  

   bases 
  of 
  the 
  crura. 
  On 
  either 
  side 
  of 
  

   these 
  ridges 
  and 
  just 
  within 
  the 
  mar- 
  

   gins 
  of 
  the 
  valve 
  is 
  a 
  strong, 
  oval, 
  

   concave, 
  pouch-like 
  plate. 
  The 
  crura 
  

   are 
  very 
  long, 
  passing 
  into 
  the 
  primary 
  of 
  r 
  x 
  

   lamellae 
  without 
  interruption. 
  The 
  showin 
  £ 
  cardinal 
  process, 
  marginal 
  

  

  pouches, 
  spiral 
  and 
  jugum. 
  (David- 
  

  

  spirals 
  are 
  relatively 
  small, 
  situated 
  son). 
  3 
  

   anteriorly, 
  and 
  consist 
  of 
  seven 
  or 
  eight 
  volutions. 
  These 
  are 
  

   connected 
  by 
  a 
  simple 
  erect 
  jugum, 
  which 
  is 
  situated 
  medially, 
  

  

  45 
  

  

  Interior 
  of 
  brachial 
  valve 
  

  

  