24 
DR.  R.  E.  GRANT  ON  THE  GENUS  LOLIGOPSIS, 
The  parietes  of  the  mantle  are  remarkably  thin  and  loose,  excepting  where  they  are 
supported  by  the  dorsal  transparent  lamina,  and  by  two  thin  cartilaginous  lamincB  ex- 
tending half  way  down  the  sides  of  the  mantle.  The  dorsal  lamina^  is  thin,  transparent, 
convex  externally,  carinated  along  its  middle,  narrowest  about  the  middle  of  the  trunk, 
expanded  laterally  on  the  caudal  half  of  the  trunk  in  which  the  viscera  are  lodged,  and 
tapers  gradually  to  a  narrow  point  as  it  passes  along  the  middle  of  the  circular  caudal 
fin,  to  the  lower  extremity  of  which  it  extends.  The  two  lateral  thin  lamina  present  here 
an  appearance  anomalous  in  Cephalopods ;  they  extend  longitudinally  from  the  free  edge 
of  the  mantle,  where  the  valvular  expanded  base  of  the  syphon  is  attached  internally, 
to  about  half  way  to  the  tail.  They  are  placed  rather  towards  the  ventral  surface  of 
the  mantle,  so  that  the  warty  projections  which  they  send  out  are  seen  in  the  front  view 
of  the  animal.  To  the  eye  these  lateral  laminee  are  almost  imperceptible  ;  but  they  are 
obvious  to  the  feel,  from  the  stiffness  they  produce  along  their  course.  Each  of  these 
lamina  sends  out  twelve  or  thirteen  conical  tubercles^  about  a  line  in  diameter  at  their 
base,  which  extend  to  the  distance  of  a  line  beyond  the  general  surface  of  the  mantle. 
Between  each  of  these  twelve  large  transparent  cartilaginous  warty  tubercles,  there  are 
three  minute  projecting  parts  of  the  same  substance,  the  middle  one  of  these  three  being 
larger  than  the  others,  so  that  the  whole  of  this  line  of  the  mantle  presents  a  continuous 
row  of  hard  rough  conical  prominences,  the  use  of  which  in  an  animal  otherwise  suf- 
ficiently provided  with  organs  of  progressive  motion,  it  is  not  easy  to  conceive.  When 
we  look  through  the  mantle  from  the  inside  along  the  line  of  these  tubercles,  it  appears, 
from  the  transparency  of  the  cartilaginous  substance  composing  them,  as  if  there  were 
twelve  circular  openings  on  each  side  ;  the  tubercles,  however,  are  quite  solid,  and  have 
a  very  rough  warty  external  termination.  From  their  connexion  with  the  lateral  lamina 
and  their  regular  position,  they  can  scarcely  be  considered  as  analogous  to  the  dorsal 
general  cutaneous  roughness  of  some  other  Octopods.  The  head  of  the  animal  is  sup- 
ported behind  by  its  close  attachment  to  the  upper  expanded  termination  of  the  dorsal 
lamina.  The  sac  containing  the  viscera  tapers  from  the  middle,  where  it  is  widest,  to 
the  beginning  of  the  tail,  and  continues  very  narrow  along  the  inferior  surface  to  the 
extreme  point  of  this  nearly  circular  caudal  appendix.  The  length  of  the  tail  is  about 
a  sixth  of  the  whole  length  of  the  animal ;  it  consists  of  two  semicircular  fins,  ex- 
tending laterally  from  the  posterior  termination  of  the  body.  These  fins  are  attached 
to  the  dorsal  surface  ;  they  are  supported  by  the  tapering  portion  of  the  dorsal  lamina 
throughout  their  whole  extent ;  and  by  following  that  lamina  to  its  extremity,  they  are 
drawn  a  little  out  so  as  to  terminate  the  body  in  an  obtuse  point. 
The  viscera  occupy  but  a  small  part  of  the  cavity  of  the  mantle,  and  are  placed  far 
back  in  that  cavity,  the  hranchia  themselves  not  extending  forwards  beyond  the  middle 
of  the  sac.    The  parietes  of  the  lower  part  of  the  oesophagus  are  thin,  loose,  transparent, 
and  with  internal  longitudinal  slight  plica  of  the  mucous  coat.  The  oesophagus^  narrows 
'  Fig.  2.  ^  Fig.  3.  '  Fig.  7. 
