862 
ME.  HA^mCE  ON  THE  OEGANIZATION  OF  THE  BEACHIOPODA. 
appearing  through  the  mantle ; two  lobes  of  the  ventral  surface  correspond- 
ing to  cavities  at  the  sides  of  the  foramen ; two  depressions  occasioned  by 
the  bases  of  the  crural  processes  or  oral  laminae ; m,  m,  extremities  of  anterior 
and  posterior  occlusors ; n,  liver ; o,  longitudinal  depression  for  the  reception 
of  the  dorsal  septum ; p,  ridge  formed  by  the  union  of  the  pallial  margins. 
Fig.  2.  Ventral  view  of  the  same;  the  letters  up  to  j agree  with  those  of  fig.  1: — 
Jc,  bulbous  extremity  of  intestine  seen  through  the  wall  of  the  body ; I,  edge 
of  the  ventral  mesentery;  w,  extremities  of  occlusor  muscles;  n,  ditto  of 
divaricators ; o,  ditto  of  accessory  divaricators ; ditto  of  ventral  adjustors ; 
q,  ditto  of  peduncular  muscles ; r,  peduncular  nerves ; s,  two  lobes  corre- 
sponding to  cavities  at  the  sides  of  the  foramen. 
Fig.  3.  View  of  pallial  chamber  of  the  same,  the  ventral  pallial  lobe  turned  back: — 
a,  dorsal  pallial  lobe ; b,  ventral  ditto ; c,  c,  great  pallial  sinuses  ghing 
branches  to  the  margin ; d,  d,  genitalia ; e,  e,  muscular  ties  passing  between 
the  walls  of  the  sinuses ; f,  base  of  the  membrane  suspending  the  genitalia, 
forming  a reticulated  line ; g,  circumpallial  vessel ; marginal  fold;  i,  anterior 
margin  of  divaricators ; j,  occlusors ; ventral  oviducts ; Z,  external  orifices 
leading  into  ditto ; m,  brachial  apparatus ; w,  brachial  fold ; o,  position  of  the 
mouth  concealed  by  ditto ; p,  cirri,  contracted  and  curled ; q,  oesophagus. 
Fig.  4.  Portion  of  the  alimentary  canal : — a,  stomach ; intestine ; c,  lower,  imperfo- 
rate, bulbous  extremity  of  ditto ; d,  hepatic  ducts ; e,  dorsal  mesenteiy ; 
y,  gastro-parietal  bands ; central  band ; h,  ilio-parietal  bands ; ^,  laminated 
portions  of  oriducts ; y heart  in  contracted  state ; k,  branchio-systemic  vein ; 
I,  aorta;  m,  ventral  pallial  arteries. 
Fig.  5.  Intestine  of  another  specimen: — a,  imperforate  bulbous  extremity,  the  longitu- 
dinal plications  of  the  mucous  membrane  appearing  through  the  walls ; b,  a 
transparent  line  or  ridge  corresponding  to  a groove  in  the  mucous  membrane ; 
c,  ventral  mesentery ; d,  portions  of  ilio-parietal  bands. 
Fig.  6.  Transverse  section  of  intestine: — «,  muscular  wall,  the  external  sheath  is  not 
represented ; b,  mucous  membrane,  exhibiting  large,  longitudinal  plicae ; 
c,  longitudinal  transparent  line ; d,  ventral  mesentery. 
Fig.  7.  Oviduct  as  appearing  from  the  perivisceral  chamber: — «,  laminated  portion, 
opening  into  the  peririsceral  chamber ; b,  tubular  portion ; c,  uTinkles  of  the 
lining  membrane  appearing  through  the  surface;  d,  apex  opening  externally; 
e,  accessory  pulsatile  vesicle ; f,  genital  artery ; g,  ditto,  folio-wing  the  reticu- 
lations of  the  suspending  membrane. 
Fig.  8.  Transverse  section  of  tubular  portion  of  o-viduct: — a,  lining  membrane. 
Fig.  9.  Transverse  section  of  arm : — a,  wall  of  the  great  brachial  canal ; b,  thickened  por- 
tion of  ditto ; c,  grooved  ridge ; d,  brachial  fold ; e,  roots  of  cirri ; f,  expanded 
orifices  of  ditto,  opening  into  the  efferent  brachial  canal,  g. 
Fig.  10.  Base  of  one  of  the  arms  laid  open,  exposing  the  inner  surface  of  the  great 
