﻿564 
  Setchell: 
  The 
  marine 
  spermatophytes 
  

  

  cussion 
  up 
  to 
  date. 
  The 
  greatest 
  credit 
  is 
  due 
  to 
  Ascherson 
  for 
  

   following 
  up 
  the 
  subject 
  for 
  so 
  many 
  years 
  and 
  with 
  such 
  vigor 
  as 
  

   well 
  as 
  for 
  the 
  very 
  satisfactory 
  way 
  in 
  which 
  he 
  has 
  treated 
  

   these 
  little-known 
  plants. 
  Within 
  comparatively 
  recent 
  years 
  

   Balfour 
  (1878) 
  has 
  written 
  concerning 
  the 
  morphology 
  oi 
  Halophila 
  

   and 
  Rydberg 
  (1909), 
  concerning 
  the 
  morphology 
  of 
  Thalassia 
  

   testudinum 
  Solander, 
  while 
  Ostenfeld 
  (1905, 
  1908, 
  1909 
  and 
  1916) 
  

   has 
  contributed 
  several 
  papers 
  dealing 
  with 
  the 
  morphology, 
  

  

  ecology 
  

  

  families 
  of 
  marine 
  

  

  spermatophytes. 
  

  

  The 
  ecology, 
  or 
  topographical 
  distribution, 
  of 
  the 
  marine 
  

   spermatophytes 
  is 
  fairly 
  simple 
  and 
  more 
  or 
  less 
  uniform 
  in 
  the 
  

   principal 
  details. 
  They 
  all 
  grow 
  in 
  shallow 
  water, 
  that 
  is 
  from 
  

   about 
  high-water 
  mark 
  down 
  to 
  ten 
  fathoms 
  and 
  possibly 
  in 
  

   exceptional 
  cases 
  even 
  somewhat 
  deeper. 
  The 
  species 
  of 
  PhyU 
  

   lospadix 
  are 
  usually 
  inhabitants 
  of 
  the 
  lower 
  and 
  even 
  middle 
  

   littoral 
  belts, 
  but 
  they 
  differ 
  in 
  other 
  details 
  of 
  their 
  ecology 
  from 
  

   the 
  rest 
  of 
  the 
  marine 
  spermatophytes 
  (cf. 
  Dudley, 
  1893, 
  p. 
  415). 
  

   The 
  species 
  other 
  than 
  those 
  of 
  Phyllospadix, 
  are 
  inhabitants 
  of 
  

   the 
  upper 
  sublittoral 
  belt 
  and 
  are 
  seldom 
  completely 
  uncovered 
  

   unless 
  it 
  is 
  at 
  the 
  time 
  of 
  extreme 
  low-water. 
  The 
  species, 
  also 
  

  

  padix 
  

  

  most 
  

  

  in 
  sheltered 
  places 
  although 
  some, 
  at 
  least, 
  are 
  found 
  in 
  runways 
  

  

  may 
  

  

  The 
  species 
  of 
  Phyllospadix, 
  on 
  the 
  other 
  hand, 
  prefer 
  localities 
  

   within 
  the 
  littoral 
  belt 
  where 
  they 
  are 
  exposed 
  to 
  strong 
  wave 
  

   action 
  and 
  foaming 
  surge 
  (cf. 
  Dudley, 
  1893, 
  P- 
  4I5) 
  and 
  may 
  be 
  

   classed 
  as 
  typical 
  "surge-plants" 
  or 
  "cumaphytes." 
  As 
  to 
  

   substratum, 
  the 
  great 
  majority 
  of 
  the 
  species 
  grow 
  with 
  their 
  

   long 
  and 
  prostrate 
  rhizomes 
  buried 
  more 
  or 
  less 
  deeply 
  In 
  the 
  sand 
  

  

  padi 
  

  

  comparativ 
  

  

  more 
  or 
  less 
  erect 
  and 
  condensed 
  rhizomes. 
  The 
  method 
  of 
  

   dissemination 
  of 
  Phyllospadix 
  is 
  one 
  of 
  the 
  very 
  few 
  of 
  those 
  of 
  

   the 
  marine 
  spermatophytes 
  known. 
  This 
  was 
  worked 
  out 
  in 
  the 
  

   botanical 
  laboratory 
  of 
  the 
  University 
  of 
  California 
  a 
  number 
  of 
  

   years 
  ago 
  by 
  Ralph 
  E. 
  Gibbs 
  (1902) 
  . 
  He 
  was 
  the 
  first 
  to 
  describe 
  

  

  