or  THE  EEPEODUCTIVE  OEGANS  OF  THE  ANNELIDS. 
131 
This  doubt  arises  from  a superficial  and  not  from  a real  dissimilarity.  Each  loop  is 
evidently  a correct  representative  of  a segmental  organ.  In  Chlormma  Bujardinii  (fig.  23) 
there  are  only  three  of  these  loops ; in  two  new  species  * discovered  by  the  author  they 
amount  to  four  and  six.  The  Chloraemea  are  allied  to  the  Terebellidse  in  this  parti- 
cular, that  the  segmental  organ  is  limited  to  a few  of  the  thoracic  segments.  It  is  absent 
in  the  abdominal.  The  Chloraemea  resemble  the  Nereids  and  Sabellidae  in  this  respect, 
that  neither  the  ova  nor  the  sperm-cells,  at  any  time,  are  introduced  into  the  free  cavity 
of  the  body.  No  special  expansion  of  the  blood- vascular  system  occurs  in  connexion  with 
the  apparatus  of  the  segmental  organs.  The  blood  in  every  species  is  green. 
The  Nemertine  Annelids  were  described  some  years  ago  by  De  Quateefages,  as  pre- 
senting a singular  anomaly  in  the  structure  and  disposition  of  the  generative  system.  In 
the  genera  Linens,  Borlasia  and  Nemertes  he  gave  an  elaborate  account  of  the  alimentary 
organ,  which  in  these  genera  so  prominently  occupies  the  axis  of  the  body,  under  the 
title  of  the  “ovarium.”  In  his  “Report  on  the  Annelids,”  in  1851,  the  author  con- 
tended, in  the  strongest  tei’ms,  that  the  ovarium  of  De  Quateefages  was  in  truth  “ a 
great  ahmentary  caecum ; ” observing  that  “ at  short  distances,  along  the  whole  line  of 
the  body,  on  either  side  of  the  great  ‘ caecum,’  membranous  sacculi  existed  in  the  inter- 
vals between  the  lateral  pouches  of  the  alimentary  tube,  on  which  sacculi  undoubtedly 
the  office  of  reproduction  devolved.”  This  description  has  recently,  in  all  its  details, 
been  adopted  by  an  English  writer  on  Natural  History,  without  one  word  of  acknow- 
ledgment. 
The  following  statement  is  based  upon  observations  far  more  extensive,  numerous  and 
skilled,  than  those  upon  which  the  original  “ Report  ” of  the  author  rested.  Examined 
by  itself,  and  without  the  guiding  ideas  suggested  by  the  preceding  history,  it  would 
have  been  quite  impossible  to  have  unriddled  the  mystery  of  the  reproductive  or  seg- 
mental system  of  the  Nemertidse.  So  slippery,  and  dense,  and  untransparent  are  the 
integuments,  so  completely  does  the  great  ahmentary  caecum  fill  up  the  “ cavity  of  the 
body,”  and  so  intimate  and  frequent  are  the  connective  bridles  between  its  lateral  caeca 
and  the  integuments,  that  no  original  demonstration  of  any  value  could  have  been  arrived 
at.  Having  seized  the  clue,  and  knowing  what  to  look  for,  the  demonstration  of  the 
true  segmental  organs  becomes  certain  and  easy. 
They  correspond  in  number,  not  with  the  caeca  of  the  alimentary  canal,  but  with  the 
annuli  of  the  body.  The  marks  of  these  annuli  are  not  written  on  the  exterior  tegu- 
mentary surface ; they  are  distinguished  only  by  the  transverse  septa  which  internally 
cross  the  carftary  space  at  regular  intervals  and  parcel  it  into  segmental  chambers.  In 
each  of  these  chambers  are  lodged  tAvo  segmental  organs,  one  on  either  side  of  the  median 
line.  In  the  female  they  contain  ova ; in  the  male,  sperm-cells.  There  is  only  one  spe- 
cies amongst  the  numerous  members  of  this  family  in  which  it  is  possible  to  demonstrate 
the  segmental  organs  in  situ  and  as  transparent  objects  under  the  microscope,  viz.  in 
Folia  quadrioculata ; it  is  a semitransparent  flesh-coloured  worm.  Sometimes,  by  a 
* Drawings  of  which  were  forwarded  to  the  Eoyal  Society  with  the  original  MS.  memoir. 
