MR.  R.  OWEN  ON  THE  ANATOMY  OF  THE  CALYPTRtEIDtE. 
209 
the  female,  and  the  testis  in  the  male,  suddenly  turns  upon  itself,  passes  dorsad  of  the 
stomach,  adhering  to  the  roof  of  the  branchial  chamber,  and  terminates  by  a  small 
projecting  anus  on  the  right  side  of  the  orifice  of  the  branchial  chamber,  anterior  to 
the  renal,  or  mucous,  gland. 
In  the  male^  the  testis  occupies  the  apex  of  the  triangular  visceral  mass  which  is 
lodged  between  the  internal  and  external  shelly  plates  ;  it  surrounds  the  fold  of  the  in- 
testine, and  gives  off  the  vas  deferens  near  the  pylorus.  The  excretory  duct  passes  dorsad 
of  the  rectum  and  stomach,  inclines  dextrad,  and  runs  along  a  groove  to  the  outer  side 
of  the  base  of  the  penis,  which  it  there  penetrates  :  its  disposition  within  the  intro- 
mittent  organ  I  have  not  been  able  to  determine  satisfactorily. 
The  ovarium  in  the  female  occupies  a  corresponding  situation  to  the  testis  in  the  male, 
and,  like  it,  is  in  close  contact  with  the  concave  side  of  the  branchial  chamber.  It  is 
of  considerable  size  in  the  large  specimens,  forming  the  principal  mass  of  the  viscera. 
The  oviduct  in  these  specimens  projects  a  little  from  the  mantle  :  it  terminates  posterior 
to  the  anus,  as  above  described.  A  mucous  gland,  probably  analogous  to  a  renal  organ, 
is  lodged  in  a  membranous  chamber,  about  3  lines  in  length  and  2  in  breadth,  close  to 
the  termination  of  the  rectum,  at  the  entrance  of  the  branchial  chamber.  It  consists  of 
a  glandular  part,  of  a  light  brown  colour,  and  fibrous  texture  when  seen  under  the  lens; 
though  from  analogy  the  apparent  fibres  are  no  doubt  secreting  tubes.  By  the  side  of 
this  gland  there  is  a  bag  appropriated  to  receive  the  secretion,  which  bag  or  dilated 
duct  communicates  with  the  termination  of  the  oviduct  in  the  female,  in  which  sex 
this  gland  is  larger  than  in  the  male. 
The  heart  is  readily  distinguishable,  by  the  colour  of  the  ventricle,  through  the  trans- 
parent j^ericarc^iwrn,  which  is  situated  on  the  left  side  of  the  stomach.  The  branchial 
vein  receives  the  blood  from  the  branchial  filaments  by  a  vessel  which  runs  along  the 
dorsal  aspect  of  the  base  of  the  filaments,  a  little  above  their  inserted  extremities  :  three 
or  four  veins  from  this  marginal  vessel  anastomose  upon  the  roof  of  the  branchial  cham- 
ber, and  communicate  by  a  common  trunk  with  the  auricle.  The  veins  of  the  body  run 
over  the  floor  of  the  branchial  chamber,  and  terminate  in  a  marginal  vessel  which  runs 
parallel  with  the  inserted  extremities  of  the  branchial  filaments.  From  this  vessel,  a 
small  branch  is  given  off  to  each  filament,  which,  under  the  microscope,  may  be  seen 
to  turn  over  the  free  extremity  of  the  central  horny  support,  and  passing  down  the  op- 
posite side,  to  enter  the  branchial  vein.   This  is  analogous  to  the  structure  of  the  tem- 
'  My  first  dissections  were  of  female  specimens  of  Cali/ptrira,  as  all  that  I  then  possessed  were  of  that  sex ; 
but  since  the  reading  of  this  Paper  I  have  met  with  a  male  Calypeopsis  in  the  collection  made  by  Capt.  P.  P. 
King,  and  have  been  favoured  with  a  second  male  specimen  of  Calyptraa  by  the  kindness  of  J.  E.  Gray,  Esq., 
from  which  specimens  the  above  account  of  the  male  organs  is  derived. 
