The  following  list  includes  both  fresh  and  salt  water  species ;  as  to
the  latter,  it  is  believed  to  be  reasonably  complete  for  the  very
limited  "coastline"  of  Middlesex  county.  There  is  no  rocky  shore
or  sandy  beach,  but  only  a  salt  marsh  with  muddy  banks,  extending
two  or  three  miles  up  the  Charles  and  Mystic  rivers,  so  that  only  a
very  limited  marine  flora  is  to  be  expected.  Not  uncommonly  plants
of  Laminaria,  etc.,  are  left  by  the  tide  within  our  limits,  but  as  they
are  undoubtedly  brought  from  a  distance,  they  are  not  included  here.
As  regards  fresh  water  algae,  those  species  are  given  which  are
known  to  have  been  found  in  the  county,  but  they  are  only  a  small
portion  of  what  would  be  obtained  by  a  careful  observer  who  could
give  sufficient  time  to  the  study ;  such  genera  as  Spirogyra,  Conferva,
Scytonema,  and  Oedogonium,  barely  or  not  at  all  represented  here,
are  abundantly  found  in  the  county;  so  are  also  Desmids  and
Diatoms,  which  have  been  entirely  omitted  here,  except  that  a  list  of
the  former  has  been  included,  taken  from  the  paper  by  G.  Lagerheim,
"Bidrag  till  Amerika's  Desmidie-Flora."  The  species  in  question
were  obtained  by  Lagerheim  from  specimens  of  Utricularia,  col-
lected at  Tewksbury  by  B.  D.  Greene,  and  preserved  in  Swedish
herbaria.
