58 
to  which  the  Heveas  form  part,  I will  but  briefly  quote  a few  exam- 
ples of  other  trees  whose  milk  is  useful.  The  .Apocynaceae,  the 
Sapotaceae,  the  Clusiaceae,  the  Asclepiadaceae  and  others,  are 
represented  by  useful  lactiferous  plants,  amon^  them  the  Couma 
ufiltSy  Mart.  Counla  macrocarpa , Barb.  Rod.  Plumeria  phagede- 
nica,  Muell.  Mimusops  elata^  Fr.  Allem.  Calophyllum  Brasiliense, 
Mart.  Platonia  insignis,  Mart.  Moronobia  cocchiea,  Aubl.  Sim- 
phonia  globulifera,  Linn.  f.  and  many  others,  whose  milks  produce 
rubber,  gutta  percha  and  resin. 
From  these  families  spring  the  Landolphias,  the  Castilloas,  the 
Tabernaemontanas,  the  Ficus,  the  Urceolas  and  other  exotics,  all 
of  which  have  been  of  some  benefit  to  the  rubber  industry  in  Asia, 
in  Africa  and  in  America. 
Various  are  the  species  of  Ser'uigueiras  in  the  valley  of  the 
Amazon,  but  these  are  known  only  to  the  more  intelligent  of  the 
aborigines,  some  of  whom  are  experts  in  spotting  their  differences. 
Scientili('ally  ten  species  have  been  described,  ye*t,  not  all  these 
present  the  same  properties  which  will  all  be  defined  solely  by 
their  leav'es,  since  by  this  means,  the  uninformed  will  probably  be 
able  all  the  better  to  distinguish  them,  thus  omitting  their  floral 
characters,  not  al\^'ays  within  the  power  of  every  one  to  observe. 
We  now  proceed  to  describe  the  general  sha[)e  of  the  leaves  and 
their  position,  bv  their  details,  se[)aratlng  the  species  as  follows:  — 
1.  11.  SfU'iUCKAN.A,  Mull,  jy Arg.  Leaflets  oblong-obovate,  ob- 
tusely acuminate,  sharp  at  the  base,  above  shining,  below  glaucous- 
tawny  with  glabrous  nerves  conjointed  to  small  petlolules  on  one 
petiole  with  five  glands  at  the  apex,  and  of  o »■>,  09-0^,  12x0"!, 
05,  06  in  length. 
2.  H.  Discolor,  Mull.  UArg.  Leaflets  similar  to  the  species 
above,  but  rigidly  membranous,  opacpie,  oblong-elli[)tical  or  oblong- 
obovate.  with  the  nerves  pubescent. 
3.  H.  .Me.MBKANACK.A,  Mull.  rX  Arg.  Leaflets  membranous, 
lanceolate-obovate,  straight  at  base,  acuminat(‘,  glabrous  on  both 
sides,  dark  green  above  and  glaucons-tawn  v below,  of  o oS-o 
I 5 X o 035-0  ‘‘L  055  in  lengtii. 
4.  II.  FauCIFI.ORA,  Mull.  D' Arg.  Leaflets  coriaceous  lanceo- 
late-obovate, obtusely  acuminate,  with  the  base  ac'ute,  above 
smooth,  below  glaucous,  glabrous,  of  o'^’,  io-o'>>.  i 2 x om,  05-0  n>, 
08  in  length. 
5.  II.  Kigidifolia,  Mull.  IP  Arg.  Leaflets  coriaceous,  with 
margins  recurved,  of  same  length  as  petioles,  oblong  elliptical, 
acuminate  with  the  base  acute,  rigid,  above  smooth  and  shining, 
below  glaucous,  \n  ith  the  secondary  nerves  prominent  and  of  o \ 
09-0  012  X o’n,  04-0  05  in  length.  1 
f)  II.  Nitida,  Mull.  Py Arg.  Leaflets  with  the  petioles  bi- 
glandular  at  apex,  oblong-elliptical,  \ ery  shining,  acuminate,  rigid, 
glabrous,  pale  below  and  f)t  0%  i3-o»^i,  1 8 x ni,  055-0  08  in 
length. 
7.  II.  Be.nthamiana,  Mull.  IXArg.  Leaflets  membranous, 
oblong-obovate,  of  the  size  and  form  of  Sprucen ua , pubescent  and 
below  tawny-glaucous. 
