38 
loured;  their  body  appears  to  be  very  fragile,  especially  in  the  clitel- 
lar  region.  In  the  anterior  region  the  body  is  cylindrical ,  its  posterior 
region  has  a  quadrangular  shape. 
The  tail  is  pointed.  The  anal  opening  has  a  longitudinal  triangular 
shape  and  lies  dorsally.  (Pl.  II.  fig.  19). 
The  cephalic  lobe  extends  over  a  third  of  the  buccal  segment. 
The  anterior  segments  are  large;  with  the  fourteenth  segment  their 
longitudinal  diameter  commences  to  decrease,  measuring  only  two 
third  of  the  length  of  the  anterior  segments. 
The  setae  are  situated  at  the  dorsal  and  the  ventral  side,  in 
four  couples.  In  the  anterior  third  portion  of  the  body  the  setae  of 
each  couple  are  separated  by  a  rather  great  distance,  in  the  poste- 
rior region  they  approach  each  other  closely;  in  the  latter  region  the 
dorsal  setae  are  situated  at  the  edges  of  the  dorsal  side ,  the  ventral  ones 
at  the  edges  of  the  ventral  side.  In  front  of  the  clitellum  the  dis- 
tance' between  the  setae  of  each  ventral  couple  (1  and  2)  measures 
about  the  half  of  that  between  the  two  ventral  couples;  the  distance 
between  the  ventral  and  dorsal  couples  (2  and  3)  is  somewhat  larger 
than  that  between  the  ventral  ones.  The  distance  between  the  two 
dorsal  couples  is  somewhat  larger  than  that  between  the  ventral  and 
dorsal  one.  The  distance  between  the  setae  of  each  dorsal  couple  (3 
and  4)  is  equal  to  half  the  distance  between  the  two  dorsal  couples. 
The  setae  have  the  usual  shape,  like  in  other  Lumbricidae;  in  the 
clitellar  region  they  are  longer  and  straighter,  measuring  0,35  mm., 
whereas  their  ordinary  length  is  0,28  mm. 
The  clitellum  is  characterized  by  a  folded,  crenulated  ridge,  1 
mm.  broad,  situated  laterally,  between  the  ventral  and  dorsal  cou- 
ples of  setae  (Pl.  II.  fig.  15).  This  ridge  extends  usually  over  ten  seg- 
ments, from  XXIII  to  XXXII;  sometimes  it  commences  already  in 
segment  XXII.  However  the  number  of  segments  it  occupies  is  not 
constant,  varying  from  six  or  seven  to  fourteen;  no  doubt  this  de- 
pends on  the  state  of  sexual  maturity  of  the  worms,  for  in  some  spe- 
cimens there  is  no  trace  of  the  ridge  at  all.  The  clitellum  consists 
of  glandular  elements  of  about  the  same  nature  as  in  Lumbricus,  viz. 
long,  tubular  cells  containing  a  coarsely  granular  substance,  deeply 
stained  by  alum  carmine  („glandesa  gros  corpuscules"  de  Cerfontaine) 
and  elongated ,  clubshaped  cells ,  containing  a  finely  granular  substance , 
very  slightly  stained,  except  in  its  basal  portion,  within  which  the 
