﻿4:66 
  O. 
  0. 
  Dunbar 
  — 
  Rensseherina, 
  a 
  New 
  Genus. 
  

  

  Art. 
  XLIII. 
  — 
  Rensselmrina, 
  a 
  New 
  Genus 
  of 
  Lower 
  Devonian 
  

   Brachiopods 
  / 
  by 
  Carl 
  O. 
  Dcnbar. 
  With 
  Plate 
  II. 
  

  

  [Contributions 
  from 
  the 
  Paleontological 
  Laboratory, 
  Peabody 
  Museum, 
  

  

  Yale 
  University.] 
  

  

  In 
  the 
  Linden 
  shale 
  of 
  western 
  Tennessee, 
  which 
  is 
  the 
  

   equivalent 
  formation 
  to 
  the 
  New 
  Scotland 
  of 
  New 
  York, 
  the 
  

   stout 
  dorsal 
  beaks 
  of 
  an 
  undescribed 
  Rensselceria-like 
  brachi- 
  

   opod 
  are 
  among 
  the 
  most 
  conspicuous 
  fossils, 
  although 
  the 
  rest 
  

   of 
  the 
  shell, 
  which 
  is 
  quite 
  thin, 
  is 
  far 
  less 
  often 
  preserved. 
  

   It 
  is 
  a 
  very 
  characteristic 
  species 
  in 
  the 
  southwestern 
  develop- 
  

   ment 
  of 
  the 
  New 
  Scotland 
  fauna, 
  but 
  seems 
  not 
  to 
  have 
  reached 
  

   the 
  Appalachian 
  trough. 
  Its 
  elongate 
  form 
  and 
  partially 
  pli- 
  

   cated 
  surface, 
  combined 
  with 
  its 
  specialized, 
  septate 
  brachi- 
  

   diurn, 
  preclude 
  its 
  reception 
  in 
  any 
  described 
  genus. 
  It 
  is 
  

   therefore 
  proposed 
  to 
  give 
  to 
  the 
  new 
  genus 
  which 
  it 
  repre- 
  

   sents 
  the 
  name 
  Rensselcerina, 
  because 
  of 
  its 
  nearer 
  approach 
  

   to 
  Rensselceria 
  than 
  to 
  any 
  other 
  genus 
  of 
  the 
  Centronellidse, 
  

   to 
  which 
  family 
  it 
  belongs. 
  The 
  genotype 
  is 
  Rensseherina 
  

   medioplicata, 
  n. 
  sp. 
  

  

  It 
  is 
  a 
  pleasure 
  to 
  acknowledge 
  the 
  writer's 
  obligation 
  to 
  

   Professor 
  Charles 
  Schuchert 
  of 
  Yale 
  University 
  for 
  advice 
  

   and 
  criticism 
  in 
  describing 
  the 
  new 
  genus. 
  

  

  Order 
  TELOTREMATA 
  Beecher 
  

  

  Superfamily 
  TEREBRATULACEA 
  Waagen 
  

  

  Family 
  CENTRONELLiDyE 
  Hall 
  and 
  Clarke 
  

  

  Renssel^erina, 
  new 
  genus 
  

  

  Diagnosis. 
  — 
  Shell 
  decidedly 
  elongate 
  oval, 
  often 
  nearly 
  

   cylindrical, 
  but 
  otherwise 
  having 
  the 
  general 
  form 
  of 
  the 
  later 
  

   Rensselserias, 
  though 
  always 
  less 
  broad-shouldered. 
  Shell 
  sub- 
  

   stance 
  very 
  finely 
  punctate. 
  Of 
  the 
  exterior 
  surface, 
  the 
  pos- 
  

   terior 
  half 
  and 
  the 
  lateral 
  slopes 
  of 
  the 
  shell 
  are 
  entirely 
  

   smooth 
  ; 
  but 
  anteriorly 
  the 
  median 
  portion 
  of 
  both 
  valves 
  

   bears 
  a 
  few 
  simple, 
  rounded, 
  conspicuous 
  plications 
  which 
  

   become 
  obsolete 
  about 
  half-way 
  to 
  the 
  beaks. 
  The 
  plications 
  

   are 
  separated 
  by 
  well-detined 
  concave 
  interspaces 
  that 
  are 
  at 
  

   least 
  as 
  wide 
  as 
  the 
  plications 
  themselves. 
  There 
  is 
  no 
  cardi- 
  

   nal 
  area 
  and 
  the 
  cardinal 
  and 
  lateral 
  slopes 
  are 
  rounded. 
  The 
  

   sides 
  of 
  the 
  shell 
  are 
  not 
  incurved 
  as 
  in 
  Beachia, 
  nor 
  steeply 
  

   angulated 
  as 
  is 
  commonly 
  the 
  case 
  in 
  Rensselceria. 
  The 
  

   minute 
  beak 
  of 
  the 
  dorsal 
  valve 
  is 
  concealed 
  by 
  that 
  of 
  the 
  

   ventral 
  valve, 
  which 
  is 
  strongly 
  incurved 
  and 
  closely 
  appressed 
  ; 
  

   the 
  pedicle 
  foramen 
  is 
  minute 
  and 
  neither 
  resorbed 
  nor 
  abraded 
  

   through 
  the 
  umbo. 
  

  

  