42 
rected  into  the  seminal  vesicles ,  in  stead  of  entering  the  ciliated  funnels 
of  the  sperm-ducts  lying  quite  opposite  them. 
Both  sperm-ducts  of  each  side  unite  together  in  the  middle  of  the 
Xllth  segment  and  the  common  duct ,  deeply  embedded  in  the  longitu- 
dinal muscular  layer,  above  the  series  of  the  external  ventral  bristles 
(2),  passes  straight  back  as  far  as  segment  XXVII;  it  then  sharply 
bends  itself  to  the  ventral  median  line  and  opens  on  to  the  exterior 
in  the  intersegmental  groove  of  segment  XXVII  and  XXVIII,  just 
in  the  series  of  the  internal  ventral  bristles  (Pl.  II.  figs  16  and  18). 
In  the  vicinity  of  the  external  pore  the  sperm-duct  unites  with  the 
excretory  duct  of  a  small  prostate-gland;  the  structure  of  this  gland 
could  not  be  very  well  recognized ,  but  it  seems  to  consist"  of  numer- 
ous pyriform  cells,  which  convey  their  secretion  into  a  central  duct. 
In  the  ventral  portion  of  segment  IX  I  met  with  a  curious  organ, 
(fig.  16,  x)  of  which  I  cannot  understand  the  meaning.  It  consists 
of  a  folded  membrane,  lined  with  a  layer  of  ciliated  cells,  somewhat 
resembling  the  funnel  of  a  sperm-duct  ;  opposite  to  it  a  body,  consisting  of 
spherical  cells ,  is  attached  to  the  posterior  side  of  the  anterior  septum. 
Perhaps  they  represent  a  testis  and  funnel  in  a  rudimentary  state. 
The  ovaries  have  the  usual  position  and  are  attached  to  the 
posterior  side  of  the  anterior  septum  of  segment  XIII;  they  have  a 
grape-shaped  appearance  and  contain  eggs  in  all  stages  of  development. 
Numerous  bloodvessels  traverse  the  ovaries.  The  largest  eggs  are 
situated  at  the  periphery  of  the  ovary  and  appear  to  lie  in  an  obvious 
capsule;  only  a  single  nucleolus  could  be  observed  within  them.  At 
the  posterior  side  of  the  posterior  septum,  of  segment  XIII  an  organ 
is  attached  of  about  the  same  size  as  the  ovary  and  containing  also 
a  number  of  eggs;  this  organ  represents  the  receptaculum  ovorum. 
Though  in  its  appearance  much  resembling  the  ovary,  it  is  disting- 
uished from  it  by  containing  only  large,  mature  ova,  which  are  more 
coarsely  granulated  than  the  eggs  in  the  ovary  and  ordinarily  do  not 
show  a  germinal  vesicle;  probably  this  represents  a  more  advanced 
stage  of  maturity ,  as  was  before  discussed  in  my  paper  on  Eudrilus  1). 
Like  in  other  Lumbricidae  the  receptaculum  ovorum  represents  a  sac, 
whose  cavity  is  subdivided  by  a  large  number  of  folds  growing  in- 
wards from  the  wall;  this  wall  consists  of  a  connective  membrane, 
1)  Mem.  de  la  Soc.  Zool.  de  France,  T.  Ill,  1890,  p.  223,  pl.  VIII. 
