AND  ACCOUNT  OF  A  NEW  SPECIES  OF  SEPIOLA. 
83 
dices  do  not  exist  on  the  branchial  auricles  of  Loligopsis,  where  the  hranchice  are  single 
on  each  side  as  in  other  Naked  Cephalopods.  They  consist  here  of  a  soft,  white,  fleshy, 
round  mass,  attached  by  a  very  short  broad  peduncle,  flattened  outwardly  and  concave 
in  the  middle,  but  without  any  internal  cavity  or  any  communication  with  that  of  the 
hearts,  to  which  they  are  attached.  The  branchial  hearts',  or  the  two  portions  of  the 
divided  auricle  of  this  class,  have  here  the  usual  position  at  the  base  of  the  hranchice, 
on  each  side  of  the  systemic  heart,  and  propel  the  venous  blood  along  the  margin  of 
the  ligament  connecting  each  gill  to  the  sides  of  the  mantle.  The  hranchia^  have  the 
usual  structure  and  attachments,  and  each  contains  about  twenty  pectinated  lamina  on 
each  of  its  sides.  The  form  of  these  pectinated  branchits  of  Naked  and  Testaceous  Ce- 
phalopods, and  their  lateral  position  under  the  open  mantle,  correspond  strikingly  with 
those  of  Pectinibranchiate  Gasteropods,  and  have  also  obvious  affinities  with  those  of  the 
Cyclostome  Fishes.  They  are  double  in  these  Gasteropods  as  in  Nautilus,  but  are  de- 
veloped only  on  the  left  side,  the  right  side  being  occupied  with  the  terminations  of  the 
digestive  and  the  genital  apparatus.  These  passages  in  Nautilus  and  in  the  Naked  Cepha- 
lopods terminate  on  the  median  plane  under  the  funnel,  and  thus  allow  the  two  sides  of 
the  body  to  become  symmetrically  developed,  as  in  the  higher  classes  of  animals.  The 
arterialised  blood  coming  along  the  free  margins  of  the  branchia  in  two  very  capacious 
veins,  is  poured  into  the  systemic  ventricle  at  points  not  corresponding  on  the  two  sides. 
The  systemic  heart^  is  of  a  lengthened  compressed  form,  placed  transversely  between  the 
lateral  hearts,  and  anterior  to  the  stomachs  ;  it  is  broadest  in  the  middle,  and  tapers  regu- 
larly to  the  two  extremities,  which  terminate  in  vessels  of  a  very  different  nature.  The  left 
apex  of  the  systemic  ventricle  receives  the  left  branchial  vein,  which,  as  well  as  the  right, 
is  a  little  dilated  before  it  enters  the  heart^  The  right  branchial  vein,  however,  enters 
this  ventricle  about  a  third  from  its  right  apex,  and  on  its  anterior  aspect.  The  right 
apex  of  this  lengthened  fusiform  heart  gives  origin  to  the  great  dorsal  ascending  aorta^ 
which  winds  round  on  the  right  side,  behind  the  liver  and  oesophagus,  to  ascend  to  the 
head,  along  the  middle  of  the  back  of  the  mantle.  About  a  third  from  the  left  extremity 
of  the  systemic  heart,  and  from  its  lower  margin,  comes  off  the  anterior  descending 
aorta^,  which  immediately  gives  off"  two  large  lateral  trunks^  to  the  great  glands  of  the 
oviducts  and  to  the  ovary,  and  then  bends  forwards  to  ascend  and  ramify  upon  the  an- 
terior parietes  of  the  mantle.  The  form  of  the  systemic  ventricle  varies  remarkably  in 
the  Naked  Cephalopods,  as  well  as  the  direction  in  which  it  is  extended  ;  but  there  is  great 
uniformity  in  the  distribution  of  its  vessels.  Most  generally  it  is  extended  transversely 
across  the  body,  receiving  the  arterialised  blood  by  a  single  branchial  vein  on  each  side, 
and  sending  out  a  large  dorsal  aorta,  which  ascends  to  terminate  in  the  head,  and  a  smaller 
descending  aorta,  which  bends  forwards,  after  supplying  the  genital  apparatus,  to  termi- 
nate on  the  ventral  surface  of  the  mantle.  In  Nautilus,  where  the  branchifs  are  double 
on  each  side,  this  ventricle  receives  the  blood  by  four  venous  trunks  instead  of  two. 
'  Fig.  9.  c.  c.     ^  Fig.  9././.     '  Fig.  9.        '  Tig.  9.  h.     '  Fig.  9.  k.     '  Fig.  9.  /.     '  Fig.  9.  m. 
M 
