26 
DR.  R.  E.  GRANT  ON  THE  GENUS  LOLIGOPSIS, 
markably  wide,  running  along  the  free  margin  of  each  gill  to  the  systemic  ventricle. 
There  are  twenty-two  lamincB  in  each  branchia,  which  are,  as  usual,  largest  in  the  middle 
of  the  gill,  and  become  gradually  smaller  towards  both  ends.  The  systemic  ventricle  is 
very  muscular,  though  not  larger  than  one  of  the  branchial  auricles ;  it  has  a  length- 
ened fusiform  shape,  with  an  aortal  trunk  from  each  end.  The  branchial  veins  enter 
it  on  each  side  near  its  upper  and  broader  extremity,  where  the  anterior  or  ventral 
aorta  arises ;  the  dorsal  aorta  passes  up  to  the  head  behind  the  lobes  of  the  liver. 
On  the  large  dorsal  or  posterior  aorta  there  is  a  distinct  bulbous  enlargement,  as  in 
Nautilus.  This  is  probably  the  commencement  of  the  bulbus  arteriosus,  which  in  higher 
classes  of  animals  allows  the  aorta  to  be  divided  during  the  development  of  the  vas- 
cular system,  into  the  great  pulmonic  and  systemic  trunks.  The  great  systemic  ven- 
tricle is  extended  nearly  in  a  longitudinal  direction,  and  not,  as  usual,  transversely. 
The  two  branchial  veins'  form  sHght  bulbous  enlargements  before  they  enter  near  its 
upper  and  more  dilated  part ;  and  the  anterior  or  smaller  aorta,  going  to  be  distributed 
chiefly  on  the  anterior  parietes  of  the  mantle,  has  also  a  slight  enlargement  at  its  origin 
from  this  rounded  extremity  of  the  ventricle.  The  large  dorsal  aorta,  coming  from 
the  inferior  narrow  apex  of  the  ventricle,  passes  first  downwards  and  backwards  to 
gain  the  dorsal  surface  of  the  mantle,  then  runs  upwards,  behind  the  liver  and  oeso- 
phagus, along  the  middle  of  the  back,  between  two  large  nervous  cords,  to  the  head, 
giving  off  numerous  branches  in  every  part  of  its  course.  These  two  large  parallel 
nervous  cords^  descending  along  the  middle  of  the  back,  like  the  two  columns  of  the 
spinal  marrow  of  Vertebrata,  arise  from  the  two  great  ganglia  placed  close  together  at 
the  upper  and  back  part  of  the  mantle,  and  can  be  traced  downwards,  preserving  their 
parallelism,  and  giving  olF  numerous  nerves  in  their  course,  to  the  base  of  the  mantle 
below  the  organs  of  generation.  They  take  their  course  along  the  middle  of  the  dorsal 
lamina. 
The  specimen  was  a  female,  and  the  developed  condition  of  the  ovaria  and  ova  showed 
that,  though  a  small  animal,  it  had  arrived  at  maturity.  The  ovarial  sac^  closely  at- 
tached to  the  base  of  the  stomachs,  though  filled  with  completely  developed  ova,  oc- 
cupied but  a  minute  portion  of  the  capacious  cavity  of  the  mantle  ;  all  the  viscera 
together  did  not  occupy  nearly  a  quarter  of  this  cavity.  The  ova*,  of  a  pyriform  shape 
and  nearly  of  the  same  size,  hanging  in  dense  clusters  which  distend  their  sac,  are  at- 
tached by  their  tapering  end,  and  exhibit  a  darker-coloured  opaque  central  yolk  sur- 
rounded by  a  thinner  and  more  transparent  fluid.  The  capsule  of  each  ovum  does  not 
present  the  white  opaque  reticulate  markings  so  common  in  the  larger  Cephalopods ; 
and  the  usual  large  glands  of  the  oviducts  appear  to  be  wanting. 
This  little  animal  constitutes  a  new  form  in  the  class  of  Cephalopoda,  a  highly  inter- 
esting group,  connecting,  by  obvious  characters,  the  simple  structure  of  Gasteropods 
'  Fig.  8. 
'  Figg.  5.  6, 
^  Figg.  4.  5. 
*  Figg.  9.  10. 
