﻿B. 
  Ruedemann 
  — 
  Graptolitio 
  Genus 
  Diplograptus, 
  etc. 
  453 
  

  

  Art. 
  XXXVIII. 
  — 
  Synopsis 
  of 
  the 
  Mode 
  of 
  Growth 
  and 
  

   Development 
  of 
  the 
  Graptolitic 
  Genus 
  Diplograptus 
  y* 
  by 
  

  

  E. 
  KUEDEMANN. 
  

  

  The 
  main 
  results 
  of 
  the 
  observations 
  made 
  upon 
  a 
  large 
  

   collection 
  of 
  specimens 
  of 
  the 
  genus 
  Diplograptus 
  found 
  near 
  

   Dolgeville, 
  !N". 
  Y., 
  are 
  the 
  following 
  : 
  

  

  (1) 
  Diplograptus 
  pristis 
  Hall 
  (= 
  D. 
  foliaceus 
  Murch. 
  sp.) 
  

   and 
  Diplograptus 
  pristiniformis 
  Hall 
  (= 
  D. 
  dentatus 
  Brgt. 
  

   sp.), 
  two 
  typical 
  graptolites 
  of 
  the 
  Utica 
  shale, 
  which 
  were 
  

   hitherto 
  known 
  to 
  grow 
  only 
  in 
  single 
  stipes, 
  have 
  been 
  found 
  

   growing 
  in 
  compound 
  colonial 
  stocks 
  which 
  appear 
  in 
  the 
  

   fossil 
  state 
  as 
  stellate 
  groups. 
  The 
  compound 
  fronds 
  of 
  D. 
  

   jpristis 
  Hall 
  reach 
  a 
  diameter 
  of 
  four 
  inches 
  and 
  are 
  com- 
  

   posed 
  in 
  some 
  specimens 
  of 
  as 
  many 
  as 
  forty 
  stipes, 
  those 
  of 
  

   D. 
  pristiniformis 
  Hall 
  are 
  only 
  an 
  inch 
  in 
  diameter 
  and 
  have 
  

   about 
  a 
  dozen 
  of 
  stipes. 
  

  

  (2) 
  The 
  virgulse 
  are 
  joined 
  to 
  a 
  central 
  correcting 
  stem, 
  the 
  

   " 
  funicle 
  " 
  of 
  Hall, 
  which 
  is 
  mostly 
  extended 
  to 
  a 
  vesicle 
  of 
  

   quadrangular 
  shape. 
  The 
  funicle 
  is 
  inclosed 
  in 
  a 
  thick 
  chiti- 
  

   nous 
  capsule, 
  which 
  is 
  identical 
  with 
  the 
  " 
  central 
  disc 
  " 
  of 
  the 
  

   compound 
  fronds 
  of 
  numerous 
  Monograptidod. 
  The 
  central 
  

   disc, 
  too, 
  is 
  drawn 
  out 
  at 
  the 
  four 
  corners 
  where 
  most 
  of 
  the 
  

   virgulse 
  leave, 
  so 
  as 
  to 
  appear 
  subquadrangular 
  in 
  the 
  com- 
  

   pressed 
  state. 
  

  

  (3) 
  The 
  central 
  disc 
  is 
  surrounded 
  by 
  a 
  verticil 
  of 
  oval 
  cap- 
  

   sules, 
  which 
  number 
  from 
  four 
  to 
  eight 
  and 
  probably 
  still 
  

   more. 
  The 
  latter 
  appear 
  mostly 
  as 
  oval 
  impressions 
  ; 
  in 
  a 
  few 
  

   specimens 
  a 
  thin 
  chitinous 
  film 
  is 
  discernible 
  ; 
  in 
  some 
  fossils, 
  

   however, 
  the 
  oval 
  appendage 
  is 
  made 
  up 
  of 
  distinct 
  siculse 
  

   which 
  radiate 
  from 
  an 
  axial 
  club-shaped 
  protuberance 
  within 
  

   the 
  vesicle, 
  to 
  which 
  they 
  are 
  joined 
  by 
  the 
  filiform 
  prolonga- 
  

   tion 
  of 
  their 
  pointed 
  ends. 
  The 
  mature 
  siculse 
  are 
  found 
  near 
  

   the 
  base, 
  the 
  younger 
  ones 
  toward 
  the 
  top 
  of 
  the 
  vesicle. 
  The 
  

   section 
  of 
  the 
  test 
  of 
  the 
  vesicle 
  appears 
  sometimes 
  as 
  a 
  chitin- 
  

   ous 
  ring. 
  

  

  The 
  enclosed 
  siculse 
  give 
  evidence 
  that 
  the 
  vesicles 
  were 
  

   organs 
  of 
  reproduction 
  which 
  are 
  to 
  be 
  compared 
  with 
  the 
  

   u 
  gonangia 
  " 
  of 
  recent 
  hydrozoa. 
  In 
  some 
  specimens 
  the 
  com- 
  

   pound 
  frond 
  is 
  surrounded 
  by 
  a 
  dense 
  crowd 
  of 
  siculae, 
  most 
  

   of 
  which 
  are 
  pointing 
  with 
  the 
  broad 
  ends 
  outwards, 
  so 
  as 
  to 
  

   make 
  it 
  obvious 
  that 
  they 
  took 
  their 
  origin 
  in 
  the 
  center 
  of 
  the 
  

   frond. 
  In 
  this 
  case 
  the 
  gonangia 
  were 
  apparently 
  opened 
  

   shortly 
  before 
  the 
  covering 
  of 
  the 
  fossil. 
  

  

  * 
  Abstract 
  of 
  a 
  paper 
  on 
  the 
  genus 
  Diplograptus 
  to 
  be 
  published 
  in 
  the 
  Report 
  

   ■of 
  the 
  State 
  Geologist 
  of 
  New 
  York 
  for 
  the 
  year 
  1894. 
  

  

  