Am.  Jour.  Pharm.  \ 
March,  1918.  > 
Book  Reviews. 
225 
work  on  colors.  Too  frequently  otherwise  valuable  contributions 
to  the  literature  of  art  and  science  are  impaired  by  inexactness  on 
the  part  of  the  contributor  in  expressing  the  various  color  shades.. 
Since  there  exist  a  number  of  works  on  color,  each  differing  in 
extent  and  character  of  nomenclature,  it  is  often  difficult  for  one 
to  decide  upon  the  work  to  be  followed.  There  should  be  little 
hesitancy,  however,  upon  selecting  for  comparison  and  citation  some 
one  good  color  reference,  for  it  permits  the  reader  to  find  the 
exact  color  shade  which  the  writer  desires  to  impart  to  the  character 
presented. 
The  species  of  Merulius  are  of  great  economic  importance  on 
account  of  the  dry  rot  of  timber  produced  by  those  which  grow 
on  wood.  Since  very  little  has  been  published  in  the  United  States 
concerning  decay  caused  by  many  of  our  common  species,  this 
monograph,  giving  the  names  and  descriptions  of  the  species  and 
the  kinds  of  woods  attacked  by  each,  will  doubtless  prove  ex- 
tremely valuable  alike  to  the  mycologist,  plant  pathologist  and  those 
interested  in  the  lumber  industry. 
Heber  W.  Youngken. 
Two  Exotic  Composite  in  North  America. 
J.  M.  Greenman  in  Annals  of  the  Missouri  Botanical  Garden 
for  November,  1917,  mentions  and  redescribes  two  foreign  species, 
Senecio  canabincefolius  Hook.  &  Arn.  and  Erechtites  arguta  DC, 
which  have  taken  foothold  on  North  American  soil. 
The  first  of  these,  Senecio  canabincefolius,  was  found  on  bal- 
last at  Hunter's  Wharf,  presumably  at  Pensacola,  Florida,  by  Pro- 
fessor Charles  Mohr  early  in  the  nineties,  who  referred  to  it  as 
Senecio  without  indicating  the  species.  Upon  comparison  this 
specimen  as  well  as  another  in  the  National  Herbarium  at  Wash- 
ington with  Hooker  and  Arnott's  original  description  of  Senecio 
canabincefolius,  a  South  American  species  growing  near  Buenos 
Aires,  the  writer  concludes  they  agree  in  every  detail.  He  describes 
the  plant  as  follows :  "  A  stout  herb,  glabrous  throughout,  or  slightly 
white-tomentose  on  the  under  leaf  surface;  stem  erect,  1  to  1.5  m 
high,  branched,  striate;  leaves  3  to  10  cm.  long,  mostly  deeply 
bi-tri-pinnatifid  with  few  linear  to  linear-lanceolate  divergent 
sharply  dentate  lateral  divisions ;  inflorescence  a  terminal  compound 
corymbose  many-headed  cyme;  heads  about  1  cm.  high,  radiate; 
