﻿956 
  Forty-seventh 
  Report 
  on 
  tee 
  State 
  Museum. 
  

  

  Metaplasia, 
  Hall. 
  1893. 
  

   (Plate 
  31, 
  figs. 
  21-24.) 
  

  

  Shells 
  spiriferoid 
  in 
  exterior, 
  with 
  the 
  relative 
  convexity 
  of 
  the 
  

   valves 
  reversed, 
  the 
  pedicle- 
  valve 
  bearing 
  a 
  median 
  fold 
  and 
  the 
  

   brachial 
  valve 
  a 
  broad 
  median 
  sinus. 
  

  

  The 
  teeth 
  are 
  stout 
  and 
  unsupported 
  by 
  lamellae 
  ; 
  the 
  posterior 
  

   extremities 
  of 
  the 
  diductor 
  impressions 
  in 
  the 
  pedicle-valve 
  are 
  

   deeply 
  impressed 
  and 
  separated 
  by 
  a 
  short, 
  thick 
  septum. 
  

   Anteriorly 
  the 
  muscular 
  area 
  is 
  less 
  clearly 
  denned 
  ; 
  from 
  its 
  

   distal 
  margin 
  diverge 
  two 
  ridges 
  which 
  were 
  probably 
  of 
  vascular 
  

   origin, 
  and 
  a 
  few 
  radiating 
  furrows 
  of 
  similar 
  character 
  are 
  

   seen 
  on 
  the 
  lateral 
  portions 
  of 
  the 
  valve. 
  

  

  In 
  the 
  brachial 
  valve 
  the 
  cardinal 
  process 
  is 
  quite 
  prominently 
  

   developed 
  and 
  is 
  distinctly 
  bilobed. 
  The 
  socket 
  walls 
  are 
  

   elevated 
  and 
  recurved 
  ; 
  anteriorly 
  they 
  are 
  produced 
  into 
  short 
  

   crural 
  bases 
  which 
  are 
  not 
  free, 
  but 
  rest 
  upon 
  the 
  bottom 
  of 
  the 
  

   valve. 
  The 
  muscular 
  area 
  is 
  narrow 
  and 
  elongate 
  and 
  consists 
  

   of 
  a 
  pair 
  of 
  central 
  adductor 
  scars 
  embraced 
  posteriorly 
  by 
  a 
  

   broader 
  pair. 
  From 
  the 
  anterior 
  margin 
  of 
  this 
  area 
  arise 
  two 
  

   vascular 
  trunks 
  which 
  diverge 
  outwardly 
  and 
  recurve, 
  following 
  

   the 
  margins 
  of 
  the 
  valve. 
  These 
  give 
  off 
  a 
  series 
  of 
  branches 
  

   externally 
  and 
  probably 
  a 
  shorter 
  series 
  toward 
  the 
  center 
  of 
  

   the 
  valve. 
  The 
  ovarian 
  markings 
  are 
  very 
  distinct 
  about 
  the 
  

   bases 
  of 
  the 
  dental 
  sockets. 
  Brachial 
  supports 
  unknown. 
  

  

  The 
  external 
  surface 
  of 
  the 
  shell 
  is 
  smooth 
  or 
  covered 
  with 
  

   very 
  fine 
  concentric 
  lines. 
  The 
  shell 
  substance 
  is 
  fibrous 
  and 
  

   apparently 
  impunctate. 
  

  

  Type, 
  Metaplasia 
  pyxidata. 
  Hall 
  (sp.). 
  Oriskany 
  sandstone. 
  

  

  But 
  a 
  single 
  species 
  is 
  known. 
  

  

  Verneuilia, 
  Hall. 
  1893. 
  

   (Plate 
  31, 
  figs. 
  18-20.) 
  

  

  Shells 
  spiriferoid 
  with 
  a 
  deep 
  median 
  sinus 
  on 
  each 
  valve. 
  

   The 
  exterior 
  of 
  the 
  valves 
  is 
  divided 
  by 
  two 
  strong 
  divergent 
  

   ridges 
  into 
  three 
  depressed 
  areas. 
  

  

  Type, 
  Verneuilia 
  chiroptyx, 
  d'Archiac 
  and 
  de 
  Yerneuil 
  (sp.) 
  

   Middle 
  Devonian. 
  

  

  Distribution. 
  Devonian 
  — 
  Carboniferous. 
  

  

  14: 
  

  

  