206 
There  is  little  doubt  that  Rafinesque’s  name, 
published  in  “Medical  Repository,”  2nd  Hex.,  V.,  p.  854 
(1808),  and  3rd  Hex.  II.,  p.  409  (1811),  belongs  to 
this  plant,  but  I  have  seen  no  specimen  so  named 
by  him ,  and  so  use  pensylvanicus,  of  which  I  have 
seen  the  original  specimens  named  by  Chamisso  in 
the  Berlin  herbarium.  But  in  the  Delessert  herbarium 
at  Geneva  there  is  a  specimen  from  Rafinesque  named 
fluitans ,  but  with  no  date  unfortunately,  and  it  is 
this  plant.  It  is  distributed  fairly  well  in  N.  America. 
I  have  seen  specimens  from  22  of  the  States,  and  from 
6  of  the  Provinces  of  Canada _ A.B.  See  also  in  “  The 
Naturalist,”  1908,  p.  10,  373  and  375,  where  Prof.  M.  L. 
Fern  aid,  of  Harvard,  states  that  “this  is  one  of  the 
commonest,  if  not  absolutely  the  commonest  species  from 
the  Gulf  of  St.  Lawrence  southward,  and  there  is  hardly 
a  pond  or  sluggish  stream  in  the  Eastern  United  States 
where  it  does  not  grow.  Consequently  its  fruit  could  easily 
have  got  into  manufactured  goods  at  almost  any  mill  pond. 
But  I  cannot  help  wondering  if  your  Yorkshire  plant  may 
not  be  native.  Here  are  my  reasons There  are  few,  if 
any,  clearly  introduced  Pondweeds.  P.  crispus  is  doubt¬ 
fully  native  here,  occurring  very  rarely  away  from  the 
larger  settlements,  and  usually  only  in  more  or  less 
artificial  ponds.  Otherwise  I  know  of  no  introductions 
in  America.  Nearly  all  the  Potamogetons  of  Great  Britain 
are  native  through  the  North  Eastern  United  States  and 
Canada,  wThere  they  are  associated  with  P.  epihydrum 
{P.  pensylvanicus)  ”  A  very  interesting  plant,  represented 
by  a  beautiful  series  of  specimens _ A.B.J. 
Having  all  the  circumstances  under  which  the  plant 
was  found  by  Miss  Vigurs  before  me,  I  cannot  agree  with 
Prof.  Fern  aid  that  it  may  be  a  native  species.  The  only 
species  (and  that  a  probable  hybrid)  that  is  found  in  the 
U.S.A.  and  in  England  only  is  P.  varians  (Morong)  Fryer, 
which  occurs  in  three  English  counties  and  in  one  of  the 
States.  The  real  test  for  such  as  this  would  be  to  grow 
the  American  varians  in  England,  and  the  English  plant 
in  the  U.S.,  and  see  the  result.  But  so  far  as  one  can  see 
they  are  identical,  and  in  this  Dr.  Morong  and  Mr.  Fryer 
are  agreed _ A.B. 
P.  filiformis  Nolte  ?  Shallow  pond  near  the  sea, 
Castletown,  I.  of  Man,  v.c.  71,  July  31,  1903 _ S.  Kermode 
and  C.  H.  Waddell.  Is  it  not  rather  a  P.  pectinatus  ? 
