318  MR.  R.  OWEN'S  DESCRIPTION  OF  A  MICROSCOPIC  ENTOZOON 
genus  in  his  '  Systema  Entozoorum',  but  refers  the  three  species  described  by  Zeder  to 
the  genera  Filaria  and  Ascaris.  The  Capsularia  Halecis,  or  Filaria  Capsularia  of  Ru- 
dolphi,  infests  the  abdominal  viscera  of  the  Herring,  and  measures  from  half  an  inch  to 
an  inch  in  length :  the  intestinal  canal  is  distinct,  and  is  dilated  at  one  extremity  into 
a  stomach.  In  the  males  the  intromittent  spiculum  protrudes  from  the  anal  extremity, 
which  is  the  largest.  The  Capsularia  Salaris  and  Capsularia  trinodosa  of  Zeder  repre- 
sent, according  to  Rudolphi,  a  single  species  of  Ascaris  {Asc.  Capsularia,  Rud.).  They 
are  about  an  inch  in  length,  and  are  inclosed  in  a  spiral  form  in  cysts  attached  to  the 
cellular  surface  of  the  peritoneum  of  the  Salmon.  The  Capsularia  Halecis  figured  by 
Zeder  ^  exhibits  a  straight  alimentary  canal  and  longitudinal  lines,  probably  nervous  fila- 
ments, which  resemble  those  lines  observable  under  certain  circumstances  in  the  present 
microscopic  species,  but  no  further  correspondence  in  internal  structure  can  be  traced 
between  them. 
The  circumstance  of  being  inclosed  in  cysts  is  common  to  many  very  diflferently 
organized  genera  of  Entozoa.  There  are  few  indeed,  with  the  exception  of  those  which 
live  upon  the  mucous  surfaces  of  the  body,  that  do  not,  by  exciting  the  adhesive  in- 
flammation, become  inclosed  within  an  adventitious  cyst  of  condensed  cellular  sub- 
stance analogous  to  the  galls  produced  by  the  irritation  of  larva  developed  in  the  sub- 
stance of  a  living  vegetable. 
The  simple  type  of  structure,  which  the  minute  animal  here  described  exhibits,  ap- 
proximates it  to  the  lower  organized  groups  of  the  Vers  Intestinaux  Parenchymateux  of 
Cuvier ;  and  both  from  its  locality  and  the  constancy  of  the  cyst  inclosing  it,  it  mani- 
fests a  relation  of  analogy  to  the  order  Cystica  of  Rudolphi.  From  all  the  genera  of 
this  order,  however,  it  diflfers  in  the  want  of  the  complex  armature  of  the  head  and  of 
the  dilated  vesicle  of  the  tail.  At  first  sight  it  might  seem  indicative  of  an  annectant 
group,  which  would  complete  the  circular  arrangement  of  the  Entozoa,  by  combining  the 
form  of  the  Filarioe  of  the  first,  with  some  of  the  characteristics  of  the  Cysticerci  of  the 
last,  of  Rudolphi's  orders.  Unfortunately,  however,  the  class  Entozoa  as  it  now  stands 
is  so  constituted  that  an  animal  may  be  referred  to  it  without  much  real  or  available 
knowledge  of  its  organization  being  thereby  aflforded :  it  embraces  animals  with  the 
molecular  and  animals  with  the  filiform  conditions  of  the  nervous  system  ;  conditions 
which  are  accompanied  by  different  types  of  the  digestive  system,  and  which  indicate 
not  merely  differences  of  class,  but  of  primary  division  in  the  animal  kingdom. 
The  organic  form  in  the  natural  system,  to  which  I  consider  the  animal  under  con- 
sideration as  being  most  nearly  allied,  is  that  exhibited  by  the  lower  organized  Vibriones 
of  Miiller,  and  of  which  Ehrenberg  has  composed  his  genera  Vibrio,  Spirillum,  and 
Bacterium :  so  that  the  present  species  may  be  regarded  as  affording,  with  the  seminal 
Cer caries,  a  second  example  from  the  lowest  class  of  the  animal  kingdom  having  its 
'  Naturgeschichte  der  Eingeweidewiirmer,  tab.  i.  figg.  3,  4,  5. 
