820 
ME.  IIA^^COCK  ON  THE  OEGANIZATION  OF  THE  BEACHIOPODA. 
peri\isceral  chamber,  this  would  appear  to  be  the  only  possible  conclusion,  but  can  now 
be  no  longer  maintained,  for  it  has  been  ascertained  that  more  than  one  such  passage 
exists.  The  natural  inference  would  therefore  seem  to  be,  that  the  eggs  will  find  their 
way  through  these  passages,  which  may  consequently  be  looked  upon  as  oviducts. 
These  curious  organs  were  originally  described  by  Cuyiee  as  hearts,  in  his  well-known 
memoir  on  lAnrjula  anatina^,  and  subsequently  by  Professor  Owex’^  in  the  Brachiopoda 
generally,  in  his  equally  celebrated  paper  “ On  the  Anatomy  of  the  Brachiopoda,”  pub- 
lished in  the  Transactions  of  the  Zoological  Society^.  And  up  to  the  present  time  these 
organs  are  generally  considered  as  the  blood-propelling  instruments.  They  open,  how- 
ever, as  before  stated,  externally,  and  therefore  can  have  nothing  to  do  uith  the  vascular 
system.  Any  one  who  has  the  opportunity,  and  will  take  the  necessary  pains,  may  satisfy 
liimself  of  this  fact ; but  he  must  not  be  discouraged  by  a failui’e  or  two,  for  unless  the 
specimens  be  in  excellent  condition,  he  will  find  the  determination  of  even  this  simple 
point  attended  with  considerable  difficulty.  The  epithelium,  which  is  very  deciduous  and 
brittle  in  spirit-specimens,  is  liable  to  be  crumpled  in  the  -sicinity  of  the  external  oidfices. 
It  is  consequently  a matter  of  no  little  nicety,  under  such  cii'cumstances,  to  ascertain  if 
the  openings  pass  through  the  epithelium.  It  wus  on  account  of  my  inability  to  prove 
this  that  I hesitated  with  regard  to  these  orifices  for  some  time,  even  after  they  had 
been  traced  through  the  membrane  circumscribing  the  perhisceral  chamber.  And  as 
the  subject  had  been  investigated  by  anatomists  of  the  very  highest  reputation,  it  was 
necessary,  before  calling  in  question  the  accuracy  of  their  conclusions,  to  have  the  most 
positive  evidence.  I therefore  persevered,  not  only  until  the  passage  was  demonstrated 
over  and  over  again,  but  until  the  exact  position  and  form  of  the  aperture  were  deter- 
mined beyond  the  possibility  of  doubt. 
There  are  two  of  these  oviducts  in  all  the  Brachiopods  that  have  come  under  my 
observation,  except  in  Bkynchonella,  in  which  there  are  four',  as  fii’st  pointed  out  by 
Professor  Huxley.  In  the  Terelratulidoe  they  lie  within  the  ventral  valve®,  and  may  be 
described  as  tubes  of  no  great  length,  composed  of  two  well-marked  portions,  one  being 
expanded  and  laminated,  the  other  more  strictly  tubrdar^;  these  parts  are  respectively 
the  auricle  and  ventricle  of  Professor  Owex.  The  latter  is  placed  between  the  two  mem- 
branes forming  the  anterior  wall  of  the  perivisceral  chamber,  is  curved  a little  inwards, 
and,  tapering  to  an  obtuse  point,  opens  externally  a short  way  below  the  mouth,  at  some 
little  distance  from  the  central  line  These  orifices  are  by  no  means  minute,  and  are  in 
the  form  of  slits  placed  diagonally,  having  the  occlusor  muscles  between  them.  The 
laminated  portion  lies  within  the  peri\dsceral  chamber,  and  is  much  expanded,  the  lips 
turning  over  like  those  of  a trumpet,  and  having  the  inner  surface  covered  with  strong, 
radiating,  pectinated  laminee.  In  W.  cranium  the  laminpe  are  smaller  than  usual,  and 
are  very  regular.  The  expanded  portions  are  placed  one  at  each  side  of  the  intestine, 
'■  Op.  cit.  p.  8. 
‘ Likewise  in  the  Introduction  to  Datidson’s  ‘British  Fossil  Brachiopoda,’  pp.  II,  15. 
^ Plates  LII.  fig.  10 ; LIII.  fig.  5 ; LIV.  figs.  1,  2 ; LVI.  fig.  1 ; LYII.  figs.  1,  2. 
^ Plate  LIII.  figs.  9,  10.  ^ Plate  LY.  figs.  1,  2. 
