868 
MR.  HAJNTOCK  OJs"  THE  ORGAXIZATIOX  OR  THE  BRACHIOPODA. 
2,  dorsal  mesentery';  j,  portions  of  gastro-paiietal  bands ; A’,  ilio-paiietal 
ditto ; I,  heart  in  contracted  state ; m,  branchio-systemic  vein ; enlarged 
portion  of  ditto ; o,  aorta ; one  of  the  lateral  branches  of  ditto,  dividing 
into  anterior,  q,  and  posterior,  r,  arteries ; s,  lateral  oesophageal  membrane. 
Fig.  5.  Portion  of  branchio-systemic  vein,  as  seen  in  the  compressor: — a,  outer  envelope 
or  sheath ; A,  delicate  internal  tunic ; c,  fold  or  wrinkle  of  ditto. 
Fig.  6.  Transverse  section  of  arm: — «,  anterior  or  great  brachial  canal;  i,  posterior 
ditto ; c,  c,  longitudinal  muscle  situated  in  ditto ; small  or  efferent  canal ; 
e,  grooved  ridge;  f,  bases  of  cirri;  g,  brachial  fold;  h,  blood-chaimels  in 
ditto ; ^,  ^,  epithelium ; j,  j,  thickened  cartilage-like  portions  of  the  walls  of 
the  brachial  canals. 
Fig.  7.  Transverse  section  of  arm  of  L.  anatina ; the  letters  correspond  to  those  of 
fig.  6. 
Fig.  8.  Transverse  sectiorr  of  grooved  ridge : — a,  brachial  fold ; d,  h,  bases  of  cini ; c,  small 
or  effererrt  brachial  canal ; d,  orifices  leading  from  ditto  into  cini ; e,  blood- 
chaurrels ; f,  f,  f,  f,  muscular  bands  for  the  movements  of  the  parts ; g,  ante- 
rior or  great  brachial  canal ; A,  posterior  ditto ; ^,  ^,  epithelium. 
Fig.  9.  Corpuscles  found  in  the  pallial  membranes  of  W.  australis,  supposed  to  be 
muscular. 
PLATE  LXVI. 
Fig.  1.  Dorsal  view  of  the  animal  of  L.  affinis,  the  perivisceral  chamber  partially  laid 
open : — a,  pallial  lobe ; h,  great  pallial  sinuses ; c,  a white  line  running  along 
the  outer  wall  of  ditto ; d,  d,  outer  or  lateral  branches  of  sinuses,  exhibit- 
ing a similar  white  line,  e,  irr  their  external  wall ; f,  f,  central  branches  of 
sinuses ; g,  posterior  branches  of  ditto ; h,  ramuscules  of  posterior  branches ; 
marginal  fold ; j,  extreme  pallial  margin ; the  setse  are  not  represented ; 
k,  k,  Jc,  liver,  a portion  of  which  is  removed  to  expose  the  heart,  I ; m,  portion 
of  alimentary  canal ; n,  n,  dorsal  ovaries ; o,  o,  two  coils  of  the  intestine  seen 
through  the  wall  of  the  perivisceral  chamber ; 'p,  extremities  of  anterior 
occlusors;  g,  ditto  of  posterior  ditto;  r,  ditto  of  central  adjustors;  s,  ditto 
of  external  adjustors ; t,  ditto  of  posterior  adjustors ; u,  ditto  of  divaricators ; 
V,  ditto  of  posterior  parietals ; w,  w,  margins  of  lateral  and  anterior  walls  of 
the  perivisceral  chamber. 
Fig.  2.  Ventral  view  of  the  same,  the  pallial  lobe,  a,  turned  back  to  expose  the  pallial 
chamber ; h,  dorsal  pallial  lobe ; c,  great  pallial  sinuses ; d,  d,  outer  or  lateral 
branches  of  ditto ; e,  inner  branches  of  ditto ; f,  ramuscules  of  posterior 
branches  of  ditto ; g,  extremity  of  peduncular  muscle ; h,  margirral  fold ; 
extreme  pallial  margin ; J,  marginal  setse ; A’,  A,  attenuated  caecal  extremi- 
ties of  the  lateral  pallial  sinuses ; I,  brachial  apparatus ; w,  cini ; n,  n,  bra- 
chial fold ; 0,  mouth  partially  concealed  by  ditto. 
