73 
a  violet  tint.  As  proved  by  transverse  sections  this  colour  is  due  to 
a  dark  pigment,  which  occurs  in  larges  quantities  in  the  intermus- 
cular connective  tissue,  as  well  in  the  tran versai  as  in  the  longitudi- 
nal muscular  layer,  even  in  that  under  the  peritoneal  membrane. 
The  longitudinal  diameter  of  the  segments  in  front  of  the  clitellum 
is  nearly  equal,  however  that  of  the  clitellar  segments  is  larger.  The 
first  and  second  segment  are  not  so  distinctly  separated  from  each 
other  as  the  following  ones ,  which  is  also  the  case  with  Per  ich.  capensis. 
The  cephalic  lobe  extends  with  a  broad  appendix  over  about  the 
half  of  the  buccal  segment.  The  clitellum  occupies  segment  XIII— XVII 
and  the  ventral  region  of  the  next  one.  The  male  pores  are  situated 
in  an  obvious  pit.  The  pores  of  the  two  pairs  of  spermathecae,  situated 
in  segment  VIII  and  IX,  next  to  the  median  ventral  line,  are  not 
visible  externally.  The  dorsal  pores  commence  in  the  groove  between 
segment  IV  and  V;  on  the  clitellum  they  are  very  noticeable,  as  are 
also  the  nephridial  pores. 
The  number  of  setae  upon  the  segments  in  the  vicinity  of  the 
clitellum  amounts  to  40  à  50  ;  they  are  also  present  on  the  clitellum. 
At  the  dorsal  side  the  setae  are  separated  by  an  interval  about  twice 
as  large  as  that  at  the  ventral  side;  there  is  a  narrow  gap  on  the 
median  dorsal  line. 
In  regard  of  the  internal  anatomy  can  be  stated,  that  the 
alimentary  canal  of  this  species  much  resembles  that  of  Megascolex. 
The  oesophagus  extends  till  segment  VI,  which  is  occupied  by  the 
gizzard;  the  gizzard  however  is  imperfectly  developed,  for  as  proved 
by  transverse  sections,  it  is  only  distinguished  from  the  remaining 
portion  of  the  intestinal  canal  by  the  presence  of  a  thick  layer  of 
transverse  muscular  fibres;  its  epithelium  has  no  peculiar  structure 
and  it  wants  the  thick  cuticular  investment,  found  in  the  gizzard 
of  Perichaeta  and  Megascolex. 
From  the  various  statements  about  the  gizzard  of  Perionyx-species  it 
may  be  concluded,  that  besides  by  other  characters  (above  referred  to) 
Perionyx  also  differs  from  its  congeners  by  a  rudimentary  gizzard  in 
segment  VI  (and  VII?).  Peeeiee  believed ,  that  in  P.  excavatus  the  giz- 
zard was  situated  in  segment  XII;  however  it  is  stated  by  Rosa  that 
„il  vero  ventriglio  occupa  i  segmenti  6  e  7  ;  esso  è  piccolo  e  ha  figura  di 
un  tronco  di  cono  rovesciato.  In  segmento  XII  egli  non  ha  trovato  che 
un  semplice  rigonfiamento  stomacale."  P.  arboricola,  according  to  the 
