814 
ME.  HANCOCK  ON  THE  OEGANIZATION  OE  THE  BEACHIOPODA. 
It  will  afterwards  be  seen  that  these  bands,  in  connexion  with  the  ahmentary  canal, 
have  more  important  functions  to  perform  than  that  of  merely  suspending  it  in  the 
perivisceral  chamber. 
The  digestive  organs  are  so  similar  in  the  other  two  species  of  the  TerehratvMdm 
which  have  been  examined,  that  it  is  not  necessary  to  say  much  in  respect  to  them.  In 
T.  caput-ser'pentis^  there  appears  to  be  only  two  hepatic  ducts,  and  both  in  it  and  in 
W.  cranium'^  the  intestine  is  very  short,  terminating  in  a blind  sac  before  it  reaches  the 
ventral  wall  of  the  perivisceral  chamber.  It  tapers  gradually  to  a point  which  is 
rounded,  and  suspended  in  its  place  by  the  mesentery®.  The  mucous  membrane,  lining 
the  intestinal  tube  of  W.  cranium^  is  exceeding  thick,  and  produced  into  five  or  six 
excessively  stout,  longitudinal  folds,  which  in  transverse  section*  exhibit  a p^Tamidal 
contour,  their  apices  almost  meeting  in  the  centre  of  the  tube.  In  T.  cajput-serpentis 
the  lining  membrane  is  also  very  thick ; but  from  the  state  of  the  specimens  examined 
the  character  of  the  plaits  could  not  be  determined. 
In  B.  psittacea  the  disposition  of  the  alimentary  canaP  is  the  same  as  in  the  Terehra- 
tulidce.  The  oesophagus  is,  however,  considerably  longer  than  in  Waldheimia,  the  mouth 
approaching  much  nearer  to  the  ventral  valve.  The  liver®  is  larger  than  usual,  and  the 
biliary  secretion  is  conveyed  through  the  lateral  walls  of  the  cardiac  extremity  of  the 
stomach  by  four  short  ducts,  two  at  each  side,  one  being  placed  a little  in  advance  of 
the  other. 
The  intestine  is  rather  long  and  gradually  tapers  downwards.  On  reaching  the  ven- 
tral valve,  directly  behind  the  extremities  of  the  occlusor  muscles,  it  turns  backwards 
and  upwards,  and,  detaching  itself  from  the  mesentery,  advances  a little,  and  terminates 
in  a much  enlarged,  rounded  extremity,  which  inclines  to  the  right  or  left,  varying  in 
this  respect  in  different  individuals.  The  termination  projects  freely  into  the  centre  of 
the  perivisceral  chamber,  and  here,  as  in  the  Terehratulidce,  there  is  no  anus ; the  bul- 
bous enlargement^  is  entire,  exhibiting  no  opening  whatever.  This  is  perfectly  ob'^dous 
in  Bhynchonella  psittacea,  in  which  the  facilities  of  examination  are  comparatively  great, 
on  account  of  the  terminal  portion  of  the  intestine  being  free  and  projecting  into  the 
perivisceral  cavity.  I have,  nevertheless,  made  every  endeavour  to  find  an  anal  perfora- 
tion, both  in  this  and  in  the  Terehratulidce.  I have  made  numerous  dissections  under  a 
powerful  doublet ; I have  removed  the  part  and  examined  it  with  the  microscope ; I have 
filled  the  tube  with  fluid  as  a finger  of  a glove  with  air,  and  by  pressure  have  attempted  to 
force  a passage;  I have  tried  injections;  but  have  equally,  on  all  occasions,  failed  to  dis- 
cover an  outlet,  and  have  only  succeeded  in  demonstrating  more  and  more  cleaidy  the 
csecal  nature  of  the  terminal  extremity  of  the  alimentary  canal.  Therefore,  how  much 
soever  it  may  be  opposed  to  analogy  and  to  authority,  the  fact  must  be  recorded — there 
is  no  anal  orifice  in  Waldheimia,  in  Terehratulina,  or  in  Bhynchonella. 
In  Bhynchonella  the  gastro-parietal  and  ilio-parietal  bands,  particularly  the  latter,  ai'e 
‘ Plate  LIII.  fig.  5.  ^ Plate  LIV.  fig.  2.  ^ Plate  LIV.  figs.  3,  4.  * Plate  LIV.  figs.  5,  6, 7. 
' Plate  EXI.  figs.  1,  2.  ® Plate  LXI.  figs.  3, 4.  ’ Plate  LX.  figs.  4,  5. 
