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MR.  R.  OWEN  ON  THE  ANATOMY  OF  DISTOMA  CLAVATUM. 
inch  in  breadth,  exceeding  that  in  the  Hunterian  collection  by  about  one  third ;  so 
that  Pallas  calls  it  the  giant  of  its  kind,  "  ad  aliud  quam  Fasciolaram  genus  referre 
non  potui,  in  quo  quasi  gigas  erit." 
The  Distoma  ventricosum  of  the  '  Synopsis  Entozoorum '  of  Rudolphi,  is  a  minute 
species  distinct  from  the  Fasciola  ventricosa  of  Pallas,  whose  account  appears  to  have 
escaped  the  Lyncean  eye  of  the  learned  founder  of  Entozoology.  Pallas's  species  is 
nevertheless  characterized  by  Rudolphi,  but  under  the  designation  oi  Distoma  clavatum: 
and  in  the  more  detailed  description  contained  in  the  '  Historia  Entozoorum,'  reference 
is  made  to  Mr,  Menzies'  paper  in  the  '  Linnean  Transactions  \'  where  the  species  de- 
scribed under  the  name  of  Fasciola  clavata  is  evidently  the  same  with  the  Fasciola  ven- 
tricosa of  Pallas.  Mr.  Menzies  both  describes  and  figures  the  posterior  aperture  ;  and 
this  testimony  to  the  accuracy  of  Pallas  is  perhaps  of  more  weight,  as  the  author 
supposes  that  he  is  describing  a  new  animal.  Rudolphi,  however,  both  in  the  '  Historia 
Entozoorum '  and  in  the  '  Synopsis  Entozoorum,'  doubts  the  accuracy  of  this  statement, 
and  gives  no  account  of  the  internal  structure  of  the  species. 
It  was  therefore  with  much  satisfaction  that  I  found,  on  looking  over  the  admirable 
collection  of  Invertebrate  Animals  made  by  the  late  Rev.  Lansdown  Guilding,  and  recently 
sent  to  this  country,  a  fine  specimen  of  the  Fasciola  ventricosa  sen  clavata,  of  equal  size 
with  that  figured  by  Pallas,  and  well  preserved  in  spirit  of  wine. 
The  circumstances  under  which  it  was  originally  obtained  were  not  mentioned  in  the 
manuscript  catalogue  of  Mr.  Guilding.  Pallas,  with  reference  to  the  habitat  of  the  spe- 
cies, merely  states  that  his  specimen  was  sent  from  Amboyna^.  Mr.  Menzies  observes 
that  he  often  found  the  Fasciola  clavata  in  the  maws  of  the  Bonito,  between  the  tropics 
in  the  Pacific  Ocean.  Rudolphi  also  assigns  the  stomach  of  Scomber  Pelamys  as  the 
habitat  of  the  Distoma  clavatum,  on  the  authority  of  Garsinus  and  Tilesius^. 
Mr.  Guilding's  specimen  of  this  large  species  of  Distoma  measures  2  inches  2  lines 
in  length,  and  2-^  inches  in  circumference  at  the  thickest  part.  It  closely  resembles  in 
form  the  figure  given  by  Pallas.  Mr.  Menzies,  who  observed  the  animal  in  its  living 
state,  represents  it  of  a  longer  and  more  attenuated  form.  The  outer  integument  is 
thin,  crisp,  and  semitransparent,  transversely  and  minutely  wrinkled,  and  evidently 
fibrous  in  the  same  direction :  it  adheres  but  slightly,  at  least  after  maceration  in  spirit, 
to  the  succeeding  layer.  This  tunic  is  evidently  muscular,  and  composed  of  longitu- 
dinal fibres,  and  adheres  pretty  closely  to  the  membrane  immediately  inclosing  the  cel- 
lular parenchyma  of  the  body ;  still,  by  proceeding  carefuUy,  they  can  be  separated. 
The  longitudinal  fibrous  tunic  is  beautifully  ornamented  with  tortuous  vessels,  con- 
taining a  dark-coloured  fluid. 
The  anterior  orifice,  which  is  the*  commencement  of  the  true  afimentary  canal,  is 
surrounded  by  a  muscular  sphincter,  forming  a  suctorious  disc  or  cup,  of  a  firm  and 
'  Vol.  i.  p.  187.  Plate  XVII.  fig.  2. 
*  "  Ex  Amhoyna  missum  fuit  singulare  hoc  MoUuscum." 
^  It  is  always  advisable  to  examine  the  stomach  and  intestines  of  the  Bonito,  Albicore,  and  other  tropical 
Fishes,  which  are  frequently  infested  with  singular  Entozoa. 
