﻿1874.] 
  

  

  the 
  Transit-Expedition 
  at 
  Rodriguez. 
  

  

  135 
  

  

  Eodriguez, 
  November 
  1874. 
  

  

  Sie, 
  — 
  I 
  send 
  by 
  the 
  i 
  Shearwater 
  ' 
  to-morrow, 
  for 
  transmission 
  by 
  the 
  

   mail 
  leaving 
  Mauritius 
  on 
  the 
  12th 
  instant, 
  a 
  packet 
  of 
  seeds 
  of 
  some 
  of 
  

   the 
  plants 
  of 
  this 
  island 
  ; 
  and, 
  in 
  accordance 
  with 
  my 
  instructions, 
  I 
  

   submit 
  the 
  following 
  short 
  report 
  of 
  my 
  proceedings 
  here 
  up 
  to 
  the 
  

   present 
  date. 
  

  

  I 
  have 
  paid 
  special 
  attention 
  to 
  the 
  Palms 
  and 
  Pandani. 
  Of 
  the 
  former 
  

   there 
  are 
  three 
  species 
  indigenous 
  — 
  one 
  of 
  the 
  genus 
  Latania, 
  and 
  two 
  

   belonging 
  to 
  the 
  genus 
  Areca. 
  The 
  Pandani 
  present 
  much 
  greater 
  diffi- 
  

   culty 
  in 
  their 
  determination 
  ; 
  and 
  I 
  do 
  not 
  yet 
  feel 
  in 
  a 
  position 
  to 
  fix 
  

   definitely 
  the 
  number 
  of 
  species, 
  although 
  I 
  rather 
  incline 
  to 
  the 
  idea 
  that 
  

   there 
  are 
  only 
  two 
  true 
  species. 
  My 
  collection 
  of 
  the 
  plants 
  of 
  the 
  island 
  

   now 
  numbers 
  about 
  450 
  species, 
  of 
  which 
  about 
  three 
  fourths 
  are 
  Phseno- 
  

   gams. 
  I 
  have 
  made 
  observations 
  with 
  the 
  view 
  of 
  discriminating 
  between 
  

   the 
  indigenous 
  and 
  introduced 
  vegetation, 
  but 
  there 
  are 
  several 
  plants 
  

   regarding 
  which 
  I 
  am 
  doubtful. 
  I 
  have 
  not 
  yet 
  succeeded 
  in 
  finding 
  any 
  

   marine 
  Phaenogams 
  ; 
  hitherto, 
  however, 
  I 
  have 
  not 
  devoted 
  much 
  time 
  

   to 
  the 
  marine 
  flora. 
  There 
  are 
  no 
  tree 
  ferns 
  on 
  the 
  island 
  ; 
  at 
  least 
  I 
  

   have 
  seen 
  none, 
  and, 
  as 
  far 
  as 
  I 
  can 
  learn, 
  none 
  of 
  the 
  inhabitants 
  have 
  

   seen 
  any. 
  Perns 
  are 
  represented 
  by 
  about 
  two 
  dozen 
  species 
  ; 
  mosses 
  

   and 
  freshwater 
  algae 
  are 
  not 
  abundant, 
  but 
  lichens 
  are 
  very 
  numerous, 
  

   both 
  as 
  species 
  and 
  as 
  individuals. 
  This 
  flora 
  is 
  by 
  no 
  means 
  so 
  exten- 
  

   sive 
  as 
  I 
  had 
  expected 
  ; 
  but 
  the 
  survey 
  of 
  the 
  island 
  just 
  concluded 
  by 
  

   the 
  officers 
  of 
  the 
  ' 
  Shearwater 
  ' 
  shows 
  the 
  island 
  is 
  only 
  about 
  half 
  the 
  

   size 
  it 
  was 
  previously 
  supposed 
  to 
  be, 
  it 
  being 
  only 
  11 
  miles 
  long 
  by 
  4 
  

   miles 
  broad. 
  The 
  island 
  is 
  a 
  volcanic 
  one, 
  consisting 
  of 
  a 
  succession 
  of 
  

   lava-flows, 
  radiating 
  from 
  one 
  or 
  more 
  foci 
  in 
  the 
  centre 
  of 
  the 
  island, 
  

   and 
  now 
  worn 
  away 
  so 
  as 
  to 
  form 
  a 
  series 
  of 
  more 
  or 
  less 
  parallel 
  ridges, 
  

   separated 
  by 
  deep 
  ravines. 
  These 
  lava-flows 
  are 
  composed 
  chiefly 
  of 
  a 
  

   dark 
  compact 
  basalt, 
  not 
  unfrequently 
  becoming 
  porphyritic, 
  and 
  com- 
  

   monly 
  exhibiting 
  a 
  marked 
  columnar 
  structure 
  ; 
  and 
  I 
  have 
  counted 
  as 
  

   many 
  as 
  twelve 
  such 
  flows, 
  lying 
  one 
  above 
  the 
  other, 
  separated 
  severally, 
  

   either 
  by 
  beds 
  of 
  conglomerate, 
  or 
  by 
  beds 
  of 
  laterite, 
  or 
  variously 
  coloured 
  

   clayey 
  beds. 
  Granite 
  and 
  sandstone 
  do 
  not 
  occur 
  in 
  the 
  island. 
  At 
  the 
  

   east 
  and 
  at 
  the 
  west 
  ends 
  of 
  the 
  island 
  occur, 
  the 
  only 
  non-volcanic 
  rock 
  

   in 
  the 
  island, 
  namely 
  coralline 
  limestone, 
  extending 
  in 
  huge 
  sheets 
  over 
  

   many 
  acres 
  of 
  land, 
  and 
  also 
  occurring 
  in 
  detached 
  patches 
  on 
  the 
  top 
  of 
  

   the 
  basalt, 
  often 
  nearly 
  a 
  mile 
  from 
  the 
  sea. 
  On 
  the 
  northern 
  and 
  

   southern 
  sides 
  of 
  the 
  island 
  it 
  does 
  not 
  occur 
  ; 
  but 
  on 
  the 
  southern 
  side 
  

   may 
  be 
  seen 
  some 
  raised 
  beaches, 
  marking 
  upheaval 
  there, 
  as 
  does 
  the 
  

   coralline 
  limestone 
  at 
  the 
  east 
  and 
  west 
  sides. 
  Zeolites 
  are 
  common 
  in 
  

   the 
  basalt 
  in 
  many 
  places, 
  as 
  also 
  several 
  other 
  minerals. 
  The 
  whole 
  

   rocks 
  of 
  the 
  island 
  are 
  permeated 
  by 
  iron. 
  This 
  report 
  is 
  very 
  brief 
  ; 
  

  

  