816 
ME.  H.IXCOCK  OX  THE  OEGAXIZATIOX  OE  THE  BEACHIOPODA. 
of  the  dorsal  extremities  of  the  posterior  occlusors.  These  bands  are  less  extensive  than 
their  counterparts  in  Waldheimia,  and  do  not  sheath  the  muscles  as  in  it.  They  sup- 
port, however,  stout  muscular  processes,  which  pass  inwards  from  the  paiietes  towards 
the  stomach.  There  is  no  central  gastro-parietal  band,  the  lateral  ones  being  separated 
by  a considerable  space.  The  ilio-parietal  bands  are  very  largely  developed ; they  extend 
along  the  sides  of  the  straight  portion  of  the  intestine,  and  expanding  backwards  give 
otf  each  a process  which  passes  to  the  side  wall  of  the  perhisceral  cavity.  These  pro- 
cesses give  support  to  the  pseudo-hearts,  and  then  turning  forward  stretch  along  the 
inner  margins  of  these  organs  from  end  to  end,  forming  a broadish  expansion,  projecting 
into  the  perivisceral  cavity.  The  bands  themselves  terminate  behind  at  the  right  side  of 
the  ventral  extremity  of  the  divaricator  muscle,  t^ing  down  the  posterior  end  of  the 
straight  portion  of  the  intestine.  The  terminal  extremity  of  this  tube  is  likewise  attached 
to  the  lateral  wall  by  a membrane,  which  extends  as  far  back  as  the  divaricator  muscle. 
The  liver  is  composed  of  ramified  ceeca,  and  is  of  a greenish  colour,  as  in  all  the 
Brachiopods.  The  cseca,  however,  are  smaller  than  usual,  and  are  formed  mto  den.se, 
irregular  lobules,  which  communicate  with  the  alimentary  canal  by  four  short,  veiy*  wide 
ducts.  The  largest  portion  of  this  organ  lies  above  the  canal  and  behind  the  stomach, 
and  pours  its  secretion  into  the  upper  end  of  the  intestine  by  two  lateral  ducts ; that 
on  the  left  being  a little  in  advance  of  the  other.  A duct  from  a few  small  lobules, 
situated  between  the  posterior  occlusors  and  above  the  oesophagus,  opens  through  the 
dorsal  wall  of  this  portion  of  the  canal,  a little  in  advance  of  the  stomach.  A consider- 
able mass  of  the  hepatic  organ,  lying  below  the  alimentary  canal,  communicates  with 
the  stomach  by  a large  duct,  which  penetrates  its  lower  wall. 
The  Infusoria  appear  to  be  the  chief  food  of  all  the  Brachiopods ; perhaps  the  only 
food  of  the  articulated  species.  In  the  stomach  and  intestine  of  the  latter  siliceous  cases 
of  the  Diatoinacem  are  almost  always  found,  and  sometimes  in  abundance.  Lingula, 
however,  appears  to  be  a more  general  feeder,  its  intestine  frequently  containmg  a vast 
^nriety  of  matter.  Siliceous  cases  of  Naviculw  and  other  Liatomacece  are  very  common ; 
small  Crustacea  also  occur,  and  the  spicula  of  sponges ; besides  a large  quantity  of  dark 
coloured  matter  mixed  with  setse,  probably  of  annulose  animals,  and  apparently  with 
particles  of  sand  or  mud ; something  like  vegetable  matter  may  also  be  detected.  The 
convolutions  of  the  intestine  are  generally  filled  with  faecal  refuse,  rolled  into  numerous 
round  or  oval  pellets.  No  faeces  are  ever  found  in  the  intestme  of  the  articulated 
Brachiopods. 
Eeproductive  System. 
The  Brachiopods  are  usually  considered  to  be  dioecious,  and  the  sexual  organs,  which 
in  the  TerehratulidcB  occupy  the  great  pallial  sinuses, — the  so-called  vascular  trunks, — are 
stated  to  be  ovaries  or  testes,  according  to  the  sex  of  the  individual.  There  is,  however, 
some  reason  to  doubt  the  accuracy  of  this  conclusion ; though  it  is  to  be  lamented  that 
nothing  of  a very  positive  nature  can  be  brought  to  bear  upon  this  question. 
