51 
not  to  be  a Castilloa  at  all,  but  a Perebea.  I searched  everywhere 
for  this  species  without  ever  coming  across  it,  nor  had  any  of  the 
various  experienced  native  collectors  I cjuestioneci  ever  heard  of 
any  other  but  the  Caucho  tree  (C.  Elastica) 
KosCHAY,  in  a letter  which  last  year  appeared  in  the  March  issue 
of  the  ‘‘ Tropenpflanzer  describes  four  different  Castilloa  as  oc- 
curring in  Costa  Rica.  Of  these  C.  twin,  has  already  been  men- 
tioned. Of  the  rubber  yielding  Castilloa,  the  best  is  the  one 
possessing  a whitish  bark  ; it  yields  [)lenty  of  excellent  rubber. 
Another  variety  has  a black  bark  with  a rough  and  irregular 
surface,  it  yields  a rubber  as  good  as  the  \\hite  variety,  but  the 
tree  is  rapidly  exhausted.  A further  variety  is  characterised  by  a 
reddish  bark,  very  thin  and  fragile  ; it  yields  very  little  latex,  but 
the  rubber  produced  is  of  good  quality. 
Eo  this  must  be  added  that  the  Castilloa  of  Panama  appears  to 
differ  from  all  other  known  varieties  by  the  occasionally  quite 
enormous  size  of  the  leaves.  Leaves  20  inches  in  length  occur  very 
commonly,  especially  upon  young  trees.  For  this  reason  it  has 
been  suggested  that  l.he  Castilloa  of  Panama  is  a separate  species. 
Now,  as  regards  the  trees  at  Las  Cascadas.  whih*  at  first  sight 
thev  certainly  strike  one  as  typical  Castilloa  elastica,  on  closer  ex- 
amination show  a number  of  differences  which,  at  any  rate  in  the 
absence  of  flowers,  render  the  identiheation  of  the  species  none  too 
easy.  In  the  first  instance,  the  bark  of  these  trees,  although  ^•ery 
smooth,  is  certainly  neither  vellow  nor  white,  but  a delicate  pale 
pinkish  brown.  The  leaves  even  on  the  older  trees  are  not  very 
great,  but  still  distinctly  larger  than  the  leaves  on  grown  up  trees 
of  C Elastica  in  Guatemala,  Honduras,  Nicaragua  and  Mexico. 
The  hairy  covering  on  the  lower  side  of  the  leaves  is  much  less 
striking,  but  the  young  leaf  shoots  at  the  end  of  the  -branches  ap- 
pear quite  as  densely  haired  as  those  of  any  typical  Castilloa.  Also 
the  phenomenon  above  referred  to  as  so  characteristic  of  Castilloa 
is  very  strikingly  displayed  by  all  the  Castilloa  trees  at  Las 
Cascadas. 
On  the  other  hand,  the  only  valueless  species  of  Castilloa,  C.  tunu 
is  absolutely  unknown  on  the  isthmus,  and  in  my  wandering  1 have 
never  encountered  it.  It  is  equally  certain  that  the  .Las  Cascadas 
Castilloa  is  entirely  different  from  KOSCHAV’S  black  and  red  varie- 
ties ; the  appearance  of  its  bark  could  not  possibly  be  described  in 
in  the  terms  used  by  KOSCH.AV  for  the  latter  two  trees.  In  how  far 
Koschav’s  white  Castilloa  corresponds  to  the  Las  Cascadas  tree  is 
difficult  to  say,  d'he  bark  of  the  latter  migh%  with  some  appearance 
of  justification,  be  described  in  KosCHAV’s  term  as  whitish,  but  con- 
sidering that  the  large  silvery  patches  on  it  do  not  appear  to  be  the 
actual  colour  of  the  bark,  but  seem  to  be  due  to  a lichen,  and  con- 
sidering further  that  all  the  lichen-free  portions  of  the  bark  are  by 
no  means  whitish,  but  as  I stated  before,  of  a light  pinkish  brown 
colour,  I prefer  to  adhere  to  this  latter  description. 
Taking  all  these  points  in  conjunction  it  will  readily  be  seen  that 
the  Las  Cascadas  rubber  trees  exhibit  all  the  characteristics  of 
Castilloa  elastica  in  regard  to  the  general  appearance  'of  the  tree, 
