52 
latory  bristles  only  upon  segment  XIX.  Beddard's  specimens  from 
Queensland  1  )  show  a  great  resemblance  of  characters  with  those  of 
the  Malay  Archipelago,  Beddard  however  could  not  observe  the 
bifurcation  of  the  distal  extremity  of  the  setae;  Rosa  believes, 
that  in  those  worms  the  bristles  had  lost  their  tips  by  being 
worn  off.  In  support  of  Rosa's  opinion  I  can  state,  that  the  bifur- 
cation of  the  setae  in  several  specimens  is  very  difficult  to  observe, 
and  by  no  means  so  obvious,  as  figured  by  Perrier;  on  closer  exa- 
mination of  the  setae  for  this  purpose,  I  found,  that  below  the  tip,  at 
the  concave  side ,  some  crescent  ridges  are  present,  just  like  in  Rhino- 
drilus  (Pl.  IV,  fig.  36).  Beddard  also  found  them  in  Schmarda's  P.  aré- 
nicole but  thought  them  to  be  absent  in  P.  corethrurus,  and  suggests 
that  the  first  species  could  be  distinguished  by  this  character  from  the 
latter  one.  Although  this  difference  between  the  two  species  does  not 
hold,  nevertheless  P.  arenicola  may  be  a  distinct  species,  as  it  seems 
to  have  two  pairs  of  reniform  spermathecae. 
The  setae  in  P.  corethrurus  are  situated  upon  a  circular  zone, 
in  which,  in  the  segments  in  front  of  the  girdle,  the  ordinary  glan- 
dular cells  of  the  epidermis  are  nearly  totally  absent  (Pl.  Ill,  fig.  33). 
In  this  region  however  other  peculiar  structures  are  to  be  found ,  at  first 
observed  by  Perrier  in  this  species ,  and  afterwards  also  met  with  by 
Beddard  in  the  Pontosco te-specimens  from  Queensland.  Those  bodies 
(Pl.  IV,  fig.  37),  which  are  large  in  the  anterior  segments,  consist  of  an 
obvious,  highly  refractive  wall  and  a  central  body,  deeply  stained 
by  alum  carmine.  In  transverse  sections  of  the  body-wall  they  show 
a  dome-like  shape,  and  probably  they  are  connected  with  the  surface 
by  a  tubular  canal;  in  the  middle  of  their  base  the  wall  appears  to  be 
thickened  and  bears  the  spherical  central  body.  In  the  centre  of  this 
structure  a  large ,  clear  nucleus  with  a  nucleolus  is  to  be  seen  ;  the  body 
is  surrounded  by  another  thin,  unstained  layer ,  connected  with  the  wall 
by  some  large  processes.  The  organ  lies  totally  embedded  in  the  epidermis. 
Vejdowsky  2)  at  first  compared  those  bodies  with  the  large,  pear- 
shaped  cells  of  Anachaeta,  which  substitute  the  bristles  in  this 
worm;  Beddard  of  course  shared  this  opinion,  because  it  furnishes 
a  support  for  his  theory,  according  which  the  primitive  Lumbricidae 
were  furnished  with  a  circle  of  numerous  setae  in  each  segment,  like 
1)  Proc.  of  Royal  Soc.  of  Edinburgh,  Vol.  XIV,  1887  ,  p.  160. 
2)  Monographie  der  Euchytraeiden,  p.  21. 
