﻿Report 
  of 
  the 
  State 
  Geologist. 
  

  

  997 
  

  

  have 
  been 
  extended 
  to 
  the 
  surface 
  of 
  the 
  internal 
  ridge 
  on 
  the 
  

   pedicle-valve. 
  

  

  In 
  front 
  of 
  the 
  base 
  of 
  the 
  jugum 
  the 
  primary 
  lamellae 
  become 
  

   at 
  once 
  narrow 
  and 
  delicate, 
  and 
  it 
  not 
  infrequently 
  happens, 
  in 
  

  

  Fig 
  374 
  —The 
  brachidium 
  of 
  Coelospira 
  concava. 
  Hall. 
  

  

  Fig. 
  375.— 
  Profile, 
  showing 
  the 
  elevation 
  of 
  the 
  jugum. 
  The 
  stem 
  of 
  the 
  jugum 
  is 
  probably 
  

   broken 
  and, 
  therefore, 
  shorter 
  than 
  is 
  natural. 
  

  

  preparations 
  of 
  the 
  interior, 
  that 
  the 
  more 
  fragile 
  portions 
  of 
  the 
  

   ribbon 
  are 
  lost, 
  leaving 
  only 
  the 
  umbonal 
  blades 
  and 
  the 
  jugum. 
  

   (Type, 
  Coelospira 
  concava. 
  Hall. 
  Upper 
  Silurian 
  (Clinton 
  

   group) 
  — 
  Middle 
  Devonian.) 
  

  

  Subgenus 
  Leptoccelia, 
  Hall. 
  1S59. 
  

  

  (Plate 
  39, 
  figs. 
  18-27.) 
  

  

  Shells 
  similar 
  to 
  Ccelospera. 
  in 
  general 
  contour, 
  structure 
  of 
  

   hinge, 
  cardinal 
  process, 
  muscular 
  scars 
  and 
  internal 
  septa. 
  

   though 
  of 
  larger 
  size 
  and 
  coarser 
  plication. 
  In 
  the 
  original 
  

   diagnosis 
  of 
  Leptoccelia 
  the 
  shell 
  was 
  described 
  and 
  figured 
  as 
  

   possessing 
  a 
  terebratuloid 
  loop. 
  It 
  was, 
  however, 
  distinctly 
  

   stated 
  that 
  the 
  evidence 
  of 
  this 
  structure 
  was 
  confined 
  to 
  a 
  

   single 
  specimen 
  containing 
  cavities 
  in 
  its 
  filling 
  of 
  quartz, 
  which 
  

   corresponded 
  to 
  the 
  restoration 
  given. 
  Subsequent 
  investigations 
  

   have 
  not 
  corroborated 
  this 
  observation. 
  

  

  Specimens 
  are 
  not 
  often 
  favorably 
  preserved 
  for 
  the 
  retention 
  

   of 
  the 
  brachial 
  apparatus, 
  those 
  from 
  Cumberland, 
  Maryland, 
  

   being 
  replaced 
  by 
  silica 
  and 
  often 
  filled 
  with 
  coarsely 
  crystallized 
  

   quartz, 
  while 
  those 
  from 
  New 
  York, 
  Gaspe 
  and 
  South 
  American 
  

   localities 
  are 
  usually 
  in 
  the 
  form 
  of 
  casts 
  in 
  an 
  arenaceous 
  sedi- 
  

  

  55 
  

  

  