ByC.  L.Walton 130

7.  On  the  Shell  of  Cardium  eduh.     By  C.  L.  Walton  143

8.  On  Periodicity  in  the  Abundance  of  Plaice  off  the  Mersey  Estuary.
By  R.  J.  Daniel ."..       147

9.  On  the  Results  of  a  Drift  Bottle  Experiment  made  in  1913.
ByR.  J.  Daniel 168

10.     Intensive  Study  of  the  Plankton  in  the  Irish  Sea.     Part  XII.
By  W.  A.  Herdman,  A.  Scott,  and  H.  Mabel  Lewis 176


INTRODUCTION.
Last  year  in  the  Editorial  Introduction  to  the  Report
it  was  pointed  out  that  I  was  writing  for  the  last  time  as
Professor  of  Zoology  in  the  University  of  Liverpool ;  and
now,  as  Professor  of  Oceanography  for  one  year,  I  have  the
honour  to  submit  to  the  Committee  the  last  Annual  Report
on  the  Scientific  Fisheries  work  in  which  I  can  appear  as
editor  or  compiler.  Dr.  James  Johnstone  succeeds  me  as
Professor  of  Oceanography  on  October  1st,  1920,  and  into
his  capable  hands  passes  the  production  of  these  reports  from
that  time  onwards.
98  TRANSACTIONS    LIVERPOOL    BIOLOGICAL    SOCIETY.
I  have  now  drawn  up  or  edited  twenty-eight  of  these
Reports — since  1892  when,  under  the  chairmanship  of  Mr.  John
Fell,  the  Committee  appointed  me  Honorary  Director  of  the
scientific  work  and  invited  me  to  report  annually  upon  the
sea-fisheries  investigations  carried  on  in  the  district.  I  trust
that  these  reports  may  be  regarded  by  the  Committee  as  having
done  something  towards  making  known  the  scientific  conditions
of  the  fisheries  under  their  charge,  and  as  having  made  some
contribution  to  the  knowledge  of  those  fundamental  problems
of  life  in  the  sea  that  must  underlie  all  rational  exploitation
and  administration  of  a  sea-fisheries  district.
