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MR.  R.  OWEN  ON  THE  ANATOMY  OF  LINGUATULA  T^NIOIDES. 
ruginous  colour ;  it  then  becomes  narrower,  and  afterwards  continues  of  the  same  dia- 
meter to  its  termination  at  the  anus. 
When  a  portion  of  the  oviduct  is  viewed  through  the  microscope,  its  coats  are  seen 
to  be  thin  and  transparent,  and  not  closely  embracing  the  ova,  but  thrown  into  folds 
here  and  there.  When  cut  across,  the  ova  cannot  be  squeezed  out,  but  adhere  to  the 
oviduct  and  to  each  other  by  a  fine  connecting  cellular  substance.  They  are  of  a  shghtly 
flattened  oval  form,  about  -a^th.  of  an  inch  in  the  long  and  -ri^th  in  the  short  diame- 
ter, filled  with  a  clear  yellow  finely  granular  substance.  This  is  invested  with  its  proper 
membrane,  and  on  one  side  this  membrane  recedes  from  the  outer  coat,  leaving  a  clear 
space,  where  doubtless  the  cicatricula,  or  germ,  is  situated.  The  ova  are  of  a  firm  re- 
sisting texture,  and  do  not  lose  any  of  their  form  or  contour  by  drying.  Hence  they 
may  probably  remain  long  under  very  different  circumstances,  preserving  their  vitality, 
and  ready  to  take  on  the  actions  of  development  when  in  a  fit  situation. 
Cuvier  rightly  observes  of  Linguatula  Tanioides,  "  C'est  le  ver  intestin  ou  Ton  voit  le 
mieux  le  nceud  cerebral  et  les  deux  filets  nerveux^"  M.  De  Blainville,  who  adopts  the 
observations  of  Cuvier  on  the  other  parts  of  the  anatomy  of  Linguatula,  is  silent  with 
respect  to  the  nervous  system.  Rudolphi  seems  doubtful  as  to  the  nature  of  the  chords 
which  Cuvier  describes,  and  confesses  his  inability  to  detect  a  nervous  ganglion.  This 
part  was,  however,  very  conspicuous  in  the  specimen  here  described,  such  as  it  is  deli- 
neated in  the  accompanying  figure  of  the  nervous  system.  It  is  situated  between  the 
mouth  and  the  commencement  of  the  oviduct,  and  consequently  is  suboesophageal, 
and  not  cerebral.  Eight  pairs  of  nerves  may  be  distinguished,  going  from  it  in  a  ra- 
diated manner.  The  two  anterior  filaments  pass  forwards  on  either  side  of  the  oeso- 
phagus, but  they  could  not  be  traced  to  a  junction  above  that  tube.  The  small  lateral 
filaments  terminate  at  the  bases  of  the  fossa  on  either  side  of  the  mouth.  The  posterior 
pair  are  the  largest ;  they  pass  over  the  ducts  of  the  ovaries  and  testes  immediately 
before  these  join  the  oviduct,  and  then  run  down  the  sides  of  the  ventral  aspect  of  the 
body,  about  a  line  apart  from  each  other,  at  first  wavy,  where  we  may  suppose  the 
contractions  of  the  body  to  be  greatest,  and  afterwards  straight,  gradually  becoming 
wider  and  less  distinguishable  from  the  longitudinal  fibres  of  the  integument. 
This  form  of  the  nervous  system  is  similar  to  that  which  Cuvier  originally  ascribed 
to  the  genus  Ascaris,  in  which  he  considered  as  nerves  the  two  white  chords  which 
are  continued  separately  along  either  side  of  the  abdominal  region,  from  one  end  of  the 
body  to  the  other  2.  But  repeated  examination  of  this  and  other  genera  of  Nematoidea, 
instituted  for  the  purpose  of  determining  a  preparation  of  the  Ascaris  Lumbricoides 
dissected  by  Mr.  Hunter,  to  display  its  nerves,  has  subsequently  demonstrated  the 
correctness  of  M.  Otto's  description  of  the  nervous  system  in  those  Entozoa.  In  this 
respect,  as  well  as  in  the  condition  of  the  generative  system,  Strongylus,  Ascaris,  and 
other  Nematoidea,  differ  so  widely  from  Linguatula  that  the  latter  ought  to  constitute 
the  type  of  a  distinct  order  in  the  class  Coelelmintha. 
The  disposition  of  the  nervous  system  in  Linguatula  is  in  some  respects  similar  to 
'  Regnc  Animal,  ed.  1.,  torn.  iv.  p.  35.  ^  Le9ons  d'Anat.  Comp.,  torn.  ii.  p.  357. 
