:ME.  HANCOCK  ON  THE  ORGANIZATION  OF  THE  BRACHIOPODA. 
8G7 
of  fig.  4 : — Z,  peduncular  muscle ; m,  portion  of  intestine ; ventral  lobe  of 
liver ; o,  o,  o,  ventral  ovaries ; jp,  tubular  portion  of  oviducts. 
Fig.  6.  Transverse  section  of  straight  portion  of  intestine : — «,  membranous  sheath  ; 
h,  muscular  -wall ; c,  mucous  membrane ; d,  portions  of  ilio-parietal  bands ; 
€,  transparent  line  corresponding  to  groove  in  mucous  membrane. 
Fig.  7.  A small  portion  of  the  intestine  laid  open,  exhibiting  the  plicae  of  the  mucous 
membrane : — a,  a,  transverse  plicae. 
PLATE  LXV. 
Fig.  1.  Dorsal  view  of  the  perivisceral  chamber  of  young  specimen  of  L.  anatina,  most 
of  the  muscles,  the  liver  and  genitalia  having  been  removed : — a,  dorsal  extre- 
mities of  anterior  occlusors ; h,  ditto  of  divaricators ; c,  c,  anterior  parietals  ; 
d,  posterior  ditto ; e,  e,  anterior  and  lateral  walls  of  chamber ; f,  oesophagus  ; 
g,  stomach ; h,  straight  portion  of  intestine ; i,  transparent  line  or  ridge ; 
j,  convoluted  portion  of  intestine ; k,  k,  k,  hepatic  ducts ; I,  gastro-parietal 
bands ; m,  muscles  attaching  ditto  to  valve ; n,  ilio-parietal  bands ; o,  margin 
of  ditto,  extending  along  oviducts;  g),  heart,  contracted;  q,  aorta;  r,  poste- 
rior artery ; s,  anterior  ditto ; t,  oviducts, — the  so-called  hearts ; it,  laminated 
portion  of  ditto,  that  on  the  left  side  has  the  margin  tiu'ned  back ; v,  orifice 
leading  into  oviduct. 
Fig.  2.  Dorsal  view  of  the  muscular  system  of  the  same,  all  the  viscera  having  been 
removed : — a,  posterior  parietal  muscles ; b,  anterior  ditto ; c,  c,  lateral  and 
anterior  walls  of  the  perivisceral  chamber ; d,  muscles  supporting  the  gastro- 
parietal  bands ; e,  anterior  occlusors ; f,  posterior  ditto ; g,  divaricators ; 
h,  central  adjustors;  i,i,  external  posterior  ditto;  k,  external 
arteries  or  blood-channels ; the  dotted  lines  mark  their  path  through  the 
muscles ; I,  internal  ditto. 
Fig.  3.  Dorsal  -view  of  the  viscera  of  L.  affinis,  the  dorsal  hepatic  lobes  and  ovaries 
ha\ing  been  removed : — a,  anterior  occlusors ; h,  posterior  ditto ; c,  divarica- 
tors ; d,  central  adjustors ; e,  external  ditto ; posterior  ditto ; g,  posterior 
parietals ; h,  h,  margins  of  the  lateral  and  anterior  walls  of  the  perivisceral 
chamber ; i,  i,  ventral  ovaries ; j,  oesophagus ; k,  stomach ; I,  straight  portion 
of  intestine,  exhibiting  longitudinal  ridge ; m,  convoluted  portion  of  intestine ; 
n,  terminal  portion,  or  rectum ; o,  membrane  uniting  ditto  to  the  wall  of  the 
perivisceral  chamber ; j),  heart  in  contracted  state ; q,  branchio-systemic  vein ; 
r,  aorta ; s,  gastro-parietal  bands ; t,  muscles  supporting  ditto ; u,  ilio-parietal 
bands ; v,  external  blood-channels  or  arteries. 
Fig.  4.  Lateral  view  of  alimentary  canal : — a,  mouth ; b,  oesophagus ; c,  stomach ; 
d,  straight  portion  of  intestine,  exhibiting  longitudinal  ridge;  e,  convoluted 
portion  of  ditto ; f,  terminal  portion  of  ditto ; g,  anus ; h,  h,  hepatic  ducts ; 
