43 
lined  with  a  low  layer  of  naked  cells.  On  those  places,  where  the 
eggs  are  lying,  the  wall  of  the  receptaculum  becomes  very  dilated 
and  represents  only  a  delicate  membrane.  The  receptaculum  ovorum 
is  not  immediately  connected  with  the  oviduct,  and  its  opening  lies 
somewhat  inward  from  the  funnel  of  this  duct  (Pl.  III.  fig.  20). 
There  is  a  large  number  of  spermathecae  in  segment  XIV — XIX. 
Their  number  in  different  segments  however  is  not  constant  and 
varies  from  1  to  3  pairs,  nor  do  we  find  in  the  same  segment 
always  the  same  number  on  both  sides;  sometimes  the  one  side  pos- 
sesses two ,  the  other  side  three  of  them.  Usually  I  met  with  1  pair  in 
segment  XIV  and  with  3  pairs  in  segment  XV  — XIX,  the  total  number 
thus  amounting  to  32.  The  spermatheca  of  segment  XIV  corresponds 
to  the  middle  one  of  the  three  in  the  succeeding  segments  (fig.  16). 
The  spermathecae  are  situated  in  the  anterior  region  of  each 
segment  and  open  on  to  the  exterior  in  the  intersegmental  groove 
of  the  segment  and  its  preceding  one.  In  some  specimens  the  first 
spermatheca  lies  precisely  at  the  place,  where  the  septum  between 
segment  XIII  and  XIV  arises,  so  the  pouch  is  separated  by  a 
constriction  in  two  diverticula,  of  which  the  anterior  is  situated  in 
segment  XIII,  the  posterior  in  segment  XIV.  A  similar  arrangement 
was  observed  by  Mr.  Beddard  with  some  of  the  spermathecae  of  L. 
complanatus  1).  The  two  superior  spermathecae  of  each  side  have  their 
external  opening  next  to  the  setae  of  the  dorsal  couple,  the  inferior 
of  them  opens  on  to  the  exterior  in  the  middle  of  the  lateral  region. 
Each  spermatheca  represents  a  globular  pouch,  lined  with  a  single 
layer  of  columnar  cells;  at  the  median  side  of  the  pouch  this  epithe- 
lium appears  to  be  lower  than  at  the  lateral  side. 
It  is  a  curious  fact,  that  in  several  specimens  no  spermathecae 
could  be  observed,  though  the  clitellum  was  very  obvious  and  the 
worm  possessed  well-developed  seminal  vesicles  and  ovaria. 
A  similar  statement  was  made  by  Mr.  Beddard  with  a  specimen 
of  P.  posthuma2).  Others  of  our  specimens,  with  the  clitellum 
scarcely  visible  and  without  puberty-grooves,  showed  on  transverse 
sections  only  two  spermathecae  on  each  side,  situated  in  segment 
XV— XVIII;  they  contained  no  spermatozoa.  Only  the  segments  XI 
and  XII  possessed  developing  seminal  vesicles ,  containing  unsegmented 
1)  Proc.  Royal  Society  of  Edinburgh,  1885—86,  p.  451. 
2)  Annals  and  Magaz.  of  Nat.  History,  1886,  p.  94. 
