﻿FIFTH 
  REPORT 
  OF 
  THE 
  DIRECTOR 
  I908 
  20^ 
  

  

  system) 
  at 
  Minneapolis 
  that 
  contains 
  numerous 
  fragments 
  of 
  the 
  

   thahus 
  of 
  an 
  exceedingly 
  deHcate 
  alga 
  easily 
  mistaken 
  for 
  a 
  grap- 
  

   tolite 
  on 
  account 
  of 
  the 
  regularity 
  of 
  its 
  structural 
  features. 
  

  

  The 
  specimens 
  are 
  very 
  slender 
  and 
  preserved 
  only 
  as 
  a 
  brown, 
  

   mostly 
  thin 
  film, 
  w^hich, 
  hovv^ever, 
  shows 
  very 
  plainly 
  under 
  water 
  

   or 
  glycerine. 
  Occasionally 
  also 
  thicker 
  carbonaceous 
  portions 
  are 
  

   observable. 
  They 
  consist 
  essentially 
  of 
  a 
  uniformly 
  thick 
  or 
  very 
  

   gradually 
  tapering 
  main 
  axis 
  and 
  regularly 
  arranged 
  whorls 
  of 
  very 
  

   thin, 
  filamentous 
  branches 
  which 
  from 
  their 
  position 
  in 
  all 
  speci- 
  

   mens 
  observed, 
  would 
  seem 
  to 
  have 
  sharply 
  bent 
  upward 
  outside 
  of 
  

   this 
  thickened 
  base 
  and 
  grown 
  subparallel 
  to 
  the 
  main 
  axis. 
  There 
  

   were 
  six 
  or 
  more 
  in 
  one 
  whorl. 
  No 
  conclusive 
  traces 
  have 
  been 
  

   seen 
  in 
  the 
  main 
  axis 
  of 
  either 
  transverse 
  walls, 
  indicating 
  a 
  

   segmentation 
  or 
  articulation,' 
  or 
  of 
  longitudinal 
  walls 
  suggesting 
  

   a 
  composition 
  of 
  thecal 
  tubes 
  of 
  graptolitic 
  character.^ 
  The 
  absence 
  

   of 
  the 
  latter 
  partitions 
  is 
  also 
  suggested 
  by 
  the 
  smooth 
  outside 
  of 
  

   the 
  main 
  branch. 
  

  

  On 
  account 
  of 
  the 
  arrangement 
  of 
  the 
  branchlets 
  in 
  close 
  whorls 
  

   on 
  the 
  main 
  branch 
  and 
  the 
  absence 
  of 
  a 
  further 
  division 
  of 
  the 
  

   branchlets, 
  either 
  by 
  bifurcation 
  or 
  formation 
  of 
  whorls, 
  this 
  species 
  

   is 
  best 
  brought 
  under 
  Chaetocladus, 
  although 
  it 
  will 
  be 
  noticed 
  that 
  

   it 
  represents 
  a 
  transitional 
  form 
  between 
  the 
  extremely 
  densely 
  

   whorled 
  Chaetocladus 
  p 
  1 
  u 
  m 
  u 
  1 
  a 
  Whitfield 
  that 
  possesses 
  

   hardly 
  any 
  further 
  division 
  and 
  Callithamnopsis 
  delica- 
  

   t 
  u 
  1 
  a 
  that 
  possesses 
  like 
  whorls 
  on 
  the 
  main 
  branch 
  but 
  also 
  a 
  

   further 
  subdivision 
  of 
  the 
  branchlets 
  that 
  gives 
  it 
  the 
  habitus 
  of 
  a 
  

   Callithamnopsis. 
  

  

  The 
  most 
  interesting 
  feature 
  of 
  Chaetocladus 
  s 
  a 
  r 
  d 
  e 
  s 
  o 
  n 
  i 
  

   consists 
  in 
  the 
  bulbous 
  sv/ellings 
  of 
  the 
  bases 
  of 
  the 
  branchlets 
  

   forming 
  the 
  annuli 
  around 
  the 
  main 
  branch. 
  These 
  bulbs 
  are 
  seen 
  

   in 
  several 
  specimens 
  to 
  have 
  been 
  hollow 
  and 
  to 
  be 
  formed 
  by 
  

   thicker 
  tissue 
  [see 
  pi. 
  2, 
  fig. 
  9]. 
  They 
  may 
  therefore 
  possibly 
  

   have 
  contained 
  sexual 
  or 
  nonsexual 
  propagative 
  organs 
  and 
  corre- 
  

   spond 
  to 
  conceptacles 
  observed 
  in 
  some 
  Florideae 
  in 
  a 
  similar 
  

  

  Corematocladus 
  gen. 
  nov. 
  

   Ety. 
  Kof)rj/j.a 
  = 
  Si 
  broom, 
  h/AfJo? 
  = 
  a 
  young 
  branch 
  

   Thallus 
  composed 
  of 
  thick 
  subcylindric 
  stem 
  that 
  is 
  sur- 
  

   rounded 
  by 
  a 
  dense 
  mass 
  of 
  filamentous, 
  frequently 
  subdividing 
  

   branches. 
  Genotype, 
  Corematocladus 
  densa 
  sp. 
  nov. 
  

  

  ^ 
  In 
  regard 
  to 
  this 
  observation 
  we 
  have 
  to 
  rely 
  mainly 
  on 
  the 
  natural 
  sec- 
  

   tions 
  produced 
  by 
  the 
  splittinof 
  of 
  the 
  stem 
  through 
  the 
  middle 
  since 
  thin 
  

   sections 
  failed 
  on 
  account 
  of 
  the 
  flattening 
  of 
  the 
  stem 
  to 
  reveal 
  distinct 
  

   structures. 
  

  

  