﻿294 
  Dr. 
  H. 
  B. 
  Brady 
  on 
  a 
  neio 
  Type 
  of 
  Astrorhizidte 
  

  

  diameters, 
  roughly 
  speaking, 
  about 
  a 
  quarter 
  of 
  an 
  inch 
  and 
  

   half 
  an 
  inch 
  respectively. 
  The 
  texture 
  is 
  loosely 
  arenaceous, 
  

   and 
  the 
  specimens 
  are 
  in 
  consequence 
  exceedingly 
  fragile. 
  

  

  The 
  general 
  structural 
  features 
  can 
  almost 
  be 
  read 
  by 
  the 
  

   naked 
  eye 
  and 
  are 
  easily 
  made 
  out 
  under 
  a 
  low 
  magnifying- 
  

   power. 
  The 
  test 
  consists 
  typically 
  of 
  a 
  central 
  chamber 
  with 
  

   a 
  number 
  of 
  radiating 
  tubes, 
  either 
  simple 
  or 
  branched, 
  

   proceeding 
  from 
  it 
  and 
  extending 
  to 
  the 
  periphery, 
  the 
  sandy 
  

   investment 
  forming 
  a 
  thin 
  flat 
  layer 
  in 
  the 
  interstitial 
  spaces. 
  

   Mounted 
  in 
  Canada 
  balsam 
  and 
  viewed 
  by 
  transmitted 
  light 
  

   the 
  tubuli 
  are 
  seen 
  to 
  differ 
  considerably 
  in 
  diameter 
  in 
  the 
  

   two 
  species, 
  the 
  larger 
  form 
  having 
  the 
  smaller 
  tubuli. 
  The 
  

   central 
  cavity 
  is 
  probably 
  labyrinthic, 
  for 
  it 
  often 
  presents 
  an 
  

   irregularly 
  reticulated 
  appearance, 
  as 
  though 
  more 
  or 
  less 
  

   subdivided 
  by 
  aggregated 
  sand-grains 
  ; 
  but 
  the 
  inner 
  surface 
  

   of 
  the 
  tubuli 
  is 
  always 
  smooth 
  and 
  appears 
  to 
  have 
  a 
  uniform 
  

   chitinous 
  lining. 
  Externally 
  the 
  central 
  chamber 
  is 
  usually 
  

   marked 
  by 
  a 
  small 
  convex 
  elevation 
  and 
  the 
  tubes 
  by 
  limbate 
  

   lines, 
  generally 
  more 
  conspicuous 
  on 
  one 
  side 
  of 
  the 
  test 
  than 
  

   on 
  the 
  other. 
  

  

  Morphologically 
  the 
  new 
  forms 
  may 
  be 
  regarded 
  as 
  branched 
  

   or 
  radiate 
  Astrorhizce 
  with 
  the 
  sandy 
  investment 
  continued 
  

   between 
  the 
  arms, 
  so 
  as 
  to 
  produce 
  an 
  even, 
  rounded, 
  peri- 
  

   pheral 
  outline. 
  Several 
  specimens 
  of 
  the 
  smaller 
  species 
  

   have 
  no 
  central 
  chamber, 
  and 
  consist 
  only 
  of 
  a 
  branched 
  tube 
  

   traversing 
  a 
  thin 
  lamina 
  of 
  agglutinated 
  sand. 
  This 
  con- 
  

   dition 
  may 
  be 
  the 
  result 
  of 
  fracture 
  and 
  subsequent 
  growth, 
  

   or 
  such 
  specimens 
  may 
  correspond 
  to 
  the 
  " 
  stag's-horn 
  " 
  

   variety 
  of 
  Astrorhiza 
  arenaria 
  {' 
  Challenger 
  ' 
  Foraminifera, 
  

   pi. 
  xix. 
  figs. 
  7, 
  8). 
  

  

  Unfortunately 
  only 
  a 
  few 
  specimens 
  were 
  preserved 
  out 
  of 
  

   the 
  large 
  number 
  originally 
  obtained, 
  and 
  owing 
  to 
  their 
  

   extreme 
  fragility 
  still 
  fewer 
  are 
  now 
  left 
  for 
  examination. 
  It 
  

   is 
  always 
  difficult, 
  even 
  with 
  sufficient 
  material, 
  to 
  investi- 
  

   gate 
  the 
  nature 
  of 
  the 
  protoplasm 
  of 
  an 
  arenaceous 
  organism 
  

   of 
  this 
  sort, 
  and 
  at 
  present 
  nothing 
  can 
  be 
  said 
  as 
  to 
  the 
  

   presence 
  or 
  absence 
  of 
  a 
  nucleus. 
  The 
  central 
  chamber 
  and 
  

   tubuli 
  appear 
  to 
  be 
  nearly 
  filled 
  with 
  slightly 
  coloured 
  proto- 
  

   plasmic 
  matter. 
  

  

  As 
  already 
  observed, 
  both 
  species 
  were 
  abundant 
  in 
  the 
  

   localities 
  at 
  which 
  they 
  were 
  found, 
  and 
  there 
  is 
  little 
  doubt 
  

   they 
  will 
  soon 
  be 
  met 
  with 
  again 
  ; 
  meanwhile 
  the 
  following- 
  

   descriptions 
  will 
  serve 
  for 
  their 
  identification. 
  Appended 
  also 
  

   are 
  particulars 
  as 
  to 
  their 
  respective 
  habitats. 
  For 
  obvious 
  

   reasons 
  I 
  propose 
  to 
  associate 
  Mr. 
  Wood-Mason's 
  name 
  with 
  

   the 
  genus. 
  

  

  