ON  THE  INDIA-RUBBER  OF  THE  AMAZON. 
517 
leaved  seringa.  The  former  yields  most  milk,  but  neither  is  so 
productive  as  the  seringa  of  Para  [Siphonia  Brasiliensis,  Wild.). 
Both  are  straight,  tall,  and  not  very  thick  trees,  with  smoothish 
thin  bark,  and  yellow  very  odoriferous  flowers,  while  the  other 
species  have  mostly  purplish  flowers.  I  suppose  their  average 
height  may  be  about  100  feet.  I  cut  down  a  tree  of  S.  brevi- 
folia  near  San  Carlos  which  measured  110  feet.  I  first  saw  and 
gathered  S.  lutea  in  the  mouth  of  the  Uaupds  ;  and  as  I  came 
down  the  Rio  Negro  in  December,  1854,  I  found  a  ranclio  erected 
on  the  spot,  and  a  person  employed  in  extracting  rubber  from 
the  same  trees  as  I  had  taken  the  flowers. 
Near  the  Barra,  some  milk  is  taken  from  a  Siphonia  common 
on  the  river-banks  (S.  elastica,  Aubl.  ?) ;  but  there  is  another 
species  growing  in  the  interior  of  the  forest  said  to  yield  more 
milk.  I  have  not  seen  it,  and  cannot  say  whether  it  is  a  species 
known  to  me. 
The  Siphonia  most  frequent  about  the  mouths  of  the  Tapajoz 
and  Madeira  seems  to  be  S.  Spruceana,  Benth.,  but  there  are,  no 
doubt,  other  species. 
I  have  gathered,  in  all,  some  seven  or  eight  species  of  Siphonia 
on  the  Amazon  and  Rio  Negro,  but  it  is  probable  that  two  or 
three  times  as  many  still  remain  to  be  discovered. 
On  the  Uaupes,  I  met  with  two  trees*  of  a  genus  apparently 
far  removed  from  Siphofiia, — possibly  they  are  Sapotacea?,  for  I 
did  not  analyse  the  flower  {Micrandra,  Benth.  in  Journ.  of  Bot.7 
vi.,  371) — which  yield  pure  rubber,  and  are  also  called  by  the 
Indians  Xeringue  ;  but  the  clustered  trunks  (often  as  many  as 
ten  from  a  root)  and  the  simple  (not  ternate)  leaves,  give  these 
trees  an  aspect  very  different  from  that  of  the  Siphonioe. 
There  are,  doubtless,  several  other  trees  in  the  valley  of  the 
Amazon  which  yield  rubber,  but  in  many  cases  mixed  with  resin, 
which  we  have  not  here  the  means  of  separating.  Such  are  a 
great  many  Figs  and  Artocarps,  two  families  which  abound 
towards  the  head-waters  of  the  Rio  Negro  and  Oronoco.  On 
the  Casiquiare,  the  Indians  make  white  shirts  of  the  bark  of  an 
epiphytal  fig,  which  they  call  marima  blanca,  the  milk  of  which 
is  said  to  be  very  copious,  and  when  dry  elastic.    Towards  the 
*No.  2427  and  2479  to  Bentham. 
