HAJsCOCK  ON  THE  OEOANIZATION  OF  THE  BEACinOPODA. 
821 
their  inner  margins  being  supported  by  the  ilio-parietal  bands,  and  their  outer  soldered 
to  the  lateral  walls  of  the  body ; they  open  upwards  and  backwards  in  tlie  plane  of  the 
dorsal  or  posterior  sui-face  of  the  intestine. 
On  laying  these  organs  open,  the  laminge  of  the  expanded  portion  are  found  not  to 
extend  far  down,  and  to  end  abruptly ; the  lining  of  the  tubular  portion  is  thick,  sliglitly 
wi’inkled  longitudinally  next  the  laminated  portion,  and  raised  into  minute,  obtuse  villi. 
The  whole  of  the  organ  is  of  a yellow  colour,  except  in  JF.  australis,  in  which  the 
tubular  portion  is  reddish. 
It  has  been  already  stated  that  in  Mhynchonella  there  are  four  oviducts',  two  within 
the  ventral,  and  two  within  the  dorsal  valve ; both  pairs  are  precisely  similar,  and  are  of 
a yellowish  colour.  The  tubular  portion,  or  that  which  lies  between  the  tw'o  layers  of 
the  parietes,  is  ovate-oblong,  and  has  the  lining  membrane  raised  into  strong,  principally 
longitudinal,  wninkles^.  The  expanded  extremity,  though  comparatively  small,  is  well 
marked,  being  placed  rather  laterally,  and  separated  from  the  broad,  rounded  end  of  the 
tubular  portion  by  a constriction;  the  laminse  are  few  and  branched.  The  ventral  pair^ 
correspond  to  the  tw^o  in  the  Terehratididce,  and  open  externally  at  the  pointed  extre- 
mity, through  a slit  situated  as  in  them ; and  the  inner  expanded  portion  opens  througli 
the  ilio-parietal  bands,  near  to  their  junction  with  the  w'alls  of  the  body,  being  held 
within  them,  as  aptly  remarked  by  Professor  Huxley,  like  a landing-net  in  its  hoop.  Tlie 
dorsal  ones'*  lie  on  each  side  of  the  liver,  and  their  external  orifices,  w^hich  are  above  the 
mouth,  open  downwards  as  in  the  other  pair.  Their  expanded  extremities  are  suspended 
by  the  gastro-parietal  bands  close  to  the  walls  of  the  chamber ; they  open  upwards  and 
forwards. 
In  lAngida^  the  oHducts  are  rather  peculiar  in  form,  though  essentially  the  same  as  in 
the  articulated  Brachiopods ; they  are  two  in  number,  and  are  the  homologues  of  the 
ventral  pair  in  Bhynchonella,  and  consequently  equivalent  to  those  in  the  Tm^ehratididcr. 
They  lie,  to  a great  extent,  between  the  two  layers  of  the  ilio-parietal  bands,  and  are 
stretched  along  the  lateral  walls  of  the  perivisceral  chamber  from  the  front  to  behind 
the  dorsal  attachment  of  the  adjustor  muscles,  and  are  so  concealed  by  the  viscera  and 
muscles  that  very  little  of  them  can  be  seen  until  those  parts  are  removed.  The 
expanded  portions  open  upwards  and  towards  the  lateral  w'alls  of  the  body  through  the 
processes  of  the  ilio-parietal  bands  close  to  the  side  w^alls  of  the  chamber.  They  are  of 
a yellowish  colour,  small  in  proportion  to  the  other  part,  puckered  a little,  and  irregu- 
larly and  widely  laminated  in  the  interior.  The  tubular  portions  are  united  posteriorly 
to  the  former  by  exceedingly  short,  constricted  necks,  and  are  much  flattened  or  de- 
pressed; behind  they  are  enlarged  and  angulated,  and  are  attached  by  their  outer  margins 
to  the  parietes  of  the  chamber ; their  inner  margins  projecting  inwards  give  support  to 
the  folds  of  the  ilio-parietal  bands,  which  suspend  the  ventral  ovaries ; they  taper  gra- 
dually forward,  and,  curving  in  conformity  with  the  anterior  wall,  penetrate  its  substance 
’ Plate  LXI.  figs.  1,  2.  ^ Plate  LX.  figs.  7,  8.  ^ Plate  LX.  fig.  8. 
^ Plate  LV.  fig.  3.  ‘ Plates  LXIV.  figs.  2,  5 ; LXV.  fig.  1. 
