should  be  remembered,  as  Anophelmes,  with  very  rare  exceptions, 
do  not  live  in  salt  water. 
So  far  as  rivers  themselves  are  concerned,  the  only  dangerous 
parts  are  the  shallow  grass-grown  edges.  These  should  be  deepened 
where  practicable,  and  in  any  case  cleared  of  weeds.  Of  course  I  am 
referring  solely  to  the  parts  m  the  immediate  vicinity  of  towns  and 
villages.  The  rivers  and  streams  in  country  districts  need  not  be 
dealt  with.  Where  small  shallow  streams  run  through  towns,  they 
must  be  cancilzzs-d ^  so  as  to  confine  the  water  to  a  limited  area  durin*^ 
_ 
the  dry  season.  During  the  rains,  when  the  current  is  strong,  they 
are  not  dangerous. 
But  there  is  another  method  which  is  very  effective  in  pools  and 
all  standing  water,  and  which  should  always  be  adopted  in  addition 
to  the  above  measures.  I  refer  to  the  oiling  of  the  surface  of  the 
water  with  crude  kerosene.  Larvae  have  to  come  to  the  surface  to 
breathe — cover  the  surface  with  a  thin  layer  of  kerosene  oil  and  they 
are  suffocated.  This  alone  will  produce  an  enormous  diminution  in 
the  nmiiber  of  Anophelines.  It  is  especially  applicable  to  Annotto 
Bay,  where  the  pools  are  extensive  and  situated  right  in  the  middle 
of  the  town.  Crude  kerosene  is  cheap  and  it  is  very  easily  applied. 
A  long  stick  with  a  few  rags  on  the  end,  or  a  whitewash  brush  dipped 
in  a  tin  of  crude  kerosene  and  then  splashed  on  the  surface  of  the 
water,  will  form  a  film  over  a  large  area,  and  one  man  could  oil  the 
whole  of  the  pools  in  a  single  day.  As  the  larvae  take,  on  an 
average,  from  five  to  seven  days  to  breed  out,  oiling  twice  a  week 
would  be  sufficient.  I  am  informed  by  Dr.  McCatty,  a  very 
enthusiastic  and  keen  advocate  of  anti-malarial  measures,  that  the 
Parochial  Board  of  Montego  Bay  have  obtained  a  supply  of  crude 
kerosene,  and  that  oiling  the  pools  is  to  be  extensively  carried  out. 
(2)  Treatment  of  shallow  ditches  and  g’utters.  In  towns,  wherever 
it  is  possible,  these  should  be  cemented  as  is  being  done  in  Montego 
Bay,  Savanna-la-Mar,  and  other  places.  A  cemented  gutter  is  easily 
kept  clean.  But  this  work,  of  course,  will  be  gradual,  and  in  the 
meantime  they  must  be  kept  free  from  grass  and  weeds,  and  regularly 
oiled.  The  bottom  should,  so  far  as  possible,  be  levelled  so  as  to 
allow  of  an  even  flow  of  water. 
(3)  Cattle  ponds  caused  by  surface  drainage.  As  a  rule,  these 
are  not  in  the  immediate  vicinity  of  dwelling-houses,  and  in  such 
