The  classification  of  Diesing,  a  compiler  and  not  an  independent  inves-
tigator, of  the  present  group  of  organisms,  is  reproduced  (see  page  206  et
seq.)  so  far  only  as  relates  to  the  Flagellate  series,  he  exhibiting  a  keener
appreciation  of  their  most  salient  diagnostic  characters  than  had  been  dis-
played by  any  previous  authority.  Taking  on  trust  the  dictum  of  Ehren-
berg,  this  writer,  unfortunately,  fell  into  the  error  of  ascribing  to  every
member  of  this  group  the  possession  of  a  distinct  oral  aperture,  which
structure  is  abundantly  shown  in  this  manual  to  have  no  definite  existence
among  a  very  considerable  series.  Diesing's  peculiar  views  respecting  the
affinities  of  certain  of  the  Ciliata  and  Protozoa  generally  have  been  referred
to  at  length  at  page  25  of  Chapter  I.
Professor  Stein's  system,  which  may  be  cited  as  representing  the  most
advanced  views  of  Continental  biologists  with  reference  to  the  classification
and  taxonomy  of  this  highly  interesting  organic  group,  demands  more
extensive  notice.  In  its  concrete  form,  as  reproduced  at  pages  209  and  210,
such  a  tabulated  list  has  not  yet  appeared,  it  being  composed  of  the  scheme
relating  to  the  Ciliata  only,  embodied  by  Stein  in  the  second  volume  of  his
'Organismus  der  Infusionsthiere,'  published  in  the  year  1867,  to  which  is
prefixed  the  list  of  families  with  included  genera  contained  in  the  preface
to  his  recently  issued  volume,  illustrative  of  the  Flagellata,  published  at  the
close  of  the  year  1878.  As  previously  remarked,  no  diagnoses  or  descrip-
tive accounts  of  the  numerous  families,  genera,  or  species  so  abundantly  and
admirably  figured  in  this  volume  have  as  yet  appeared,  nor  is  any  attempt
made  to  subdivide  the  series  as  a  whole  into  subordinate  sections  or  orders.
