330 ;    where  c  is  the  crop ;    o,  *>*'      -^

gizzard ;  p,  a  plicated  stomach,  re

sembling  the  third  stomach  of  ru

minant  quadrupeds;  and  d,  a  fourtlKi:^
cavity,  being  that  in  which  digestioiK=i

is  completed.     A  canal  of  commu

nication  is  seen  at  t,  leading  fron^Hi
the  crop  to  this  last  cavity :  b  is  thf=3
point  where  the  biliary  duct  enters.
In    the  Cephalopoda,  the  structure  of  theses


DIGESTIVE  ORGANS  OF  FISHES.
•221


D^^ns  is  very  complicated  ;  for  they  are  pro-
vided with  a  crop,  a  muscular  gizzard,  aud  a
ceecura,  which  has  a  spiral  form,     lu  these  ani-
mals we  also  discover  the  rudiment  of  another  I
auxiliary  organ,    namely,  the   Pancreas,  which  1
secretes  a  fluid  contributing  to  the  assimilation
of  the  food.    This  organ  becomes  more  and  more
developed  as  we  ascend  in  the  scale  of  animals;
assuming  a  glandular  character,  and  secreting*  I
a  watery  fluid,  which  resembles  the  saliva,  both^
in  its  sensible  and  chemical  properties.     !t  has
been    conjectured    that    many   of  the   vessels,
which  are  attached  to  the  upper  portion  of  the
aiimentarj'   canal   of   insects,   and    have    been
termed  hepatic,  may,  in   fact,  prepare  a  fluid
having  more  of  the  qualities  of  the  pancreatic
than  of  the  biliary  secretion.
