74 
same  author,  possesses  „il  ventriglio  molto  piccolo ,  cilindrico,  poco  piu 
lungo  che  largo,  situato  nel  segmento  V."  About  P.  sansibaricus  is 
recorded  by  Michaelsen  „einen  Muskelmagen  konnte  ich  nicht  finden, 
im  Segment  XIII  zeigt  der  Oesophagus  eine  fast  kugelige  Erweiterung." 
As  to  the  intestinal  canal  of  P.  gruenewaldi  Michaelsen  mentions 
„der  Darm  modifiziert  sich  vorne  zu  einem  drüsig-muskulösen  Schlund- 
kopf. Auf  diesen  folgt  ein  langer,  enger,  von  einem  Blutsinus  innig 
umspülter  Oesophagus.  Im  Xlllem  Segment  zeigt  der  Oesophagus 
eine  fast  kugelige  Erweiterung,  die  sich  durch  die  zottige  Struktur 
der  Wandung  und  den  Blutreichthum  auszeichnet.  Eine  Ansammlung 
von  Kalkkonkrementen  zwischen  den  Zotten  der  Wandung  zeigt,  dass 
man  es  hier  mit  einem  Homologon  der  Kalkdrüsen  andrer  Terricolen 
zu  thun  hat.  In  XlVem  Segment  ist  der  Oesophagus  auffallend  glatt 
und  arm  an  Blutgefässen;  zugleich  zeigt  sich  die  Muskulatur  der 
Darm wandung  hier  etwas  verstärkt,  etwa  bis  zu  einem  Viertel  der 
Epitheldicke.  Zweifelsohne  is  diese  Modification  des  Oesophagus  als 
ein  rudimentärer  Muskelmagen  anzusehen."  I  cannot  entirely  agree 
with  Michaelsen's  statements,  for  I  found  in  the  examples  of  P. 
gruenewaldi,  which  I  could  examine,  also  a  rudimentary  gizzard  in 
segment  VI,  and  I  believe,  that  it  was  overlooked  by  him;  as  to  the 
presence  of  lime-concretions  in  the  dilated  region  of  the  intestine  in 
segment  XIII,  I  can  quite  confirm  his  observations.  In  P.  violaceus 
the  intestinal  canal  shows  also  an  annular  dilatation  in  segment  XIII , 
but  I  did  not  observe  any  lime-concretions  therein;  however  on  tran- 
verse  sections  a  wide  blood-lacuna  is  visible  here  in  the  intestinal 
wall,  which  is  highly  folded  and  covered  with  a  low  epithelium. 
Each  spermatheca  consists  of  a  large  oval  pouch,  with  a  short 
muscular  duct,  and  a  small,  stalked,  pyriform  diverticulum;  their 
microscopical  structure  agrees  with  that  of  other  allied  worms,  and 
corresponds  to  the  detailed  description  of  the  spermathecae  of  Plagio- 
chaeta,  recently  published  by  Benham.  The  main  pouch  is  totally  fil- 
led with  a  finely  granular  matter,  produced  by  the  tall  columnar 
epithelium  ;  at  the  side ,  lying  next  to  the  intestinal  canal,  the  colum- 
nar cells  are  not  so  high  as  those  in  the  remaining  portion  of  the  pouch. 
This  fact,  which  I  observed  also  in  other  spermathecae,  is  not  recor- 
ded by  Benham.  The  diverticulum  is  entirely  filled  with  spermatozoa. 
The  prostata  is  a  narrow,  tongue-shaped  body,  superficially  di- 
vided  in   lobes,  not  extending  beyond  the  XVIIIth  segment;  its 
