MR.  BRODERIP  ON  CLAVAGELLA. 
267 
of  the  supposed  solvent,  as  well  as  the  organ  for  applying  it,  may  be  so  placed  as  that 
the  solvent  shall  only  come  in  contact  with  the  inorganic  or  dead  substance  to  be  acted 
on,  without  touching  the  shell. 
Again,  it  has  been  asked,  what  solvent  would  act  equally  on  a  calcareous  and  on  a 
siliceous  substance  ?  To  this  it  may  be  answered,  first,  that  it  is  not  pretended  that 
the  nature  of  the  supposed  solvent  is  known  ;  secondly,  that,  in  siliceous  grits,  there 
is  more  or  less  calcareous  matter  by  which  the  mass  is  held  together,  and  that  the  so- 
lution of  the  calcareous  particles  would  be  followed  by  the  disintegration  of  the  stone. 
The  fossil  species  are  numerous,  and  as  yet  do  not  appear  to  have  been  detected  be- 
low the  supracretaceous  group.  One  observation,  arising  from  the  various  depths  at 
which  the  recent  species  have  been  found,  will  not  perhaps  be  deemed  irrelevant.  Clav. 
Australis  was  so  near  the  surface  at  low  water,  that  it  was  detected  by  its  ejection  of 
the  fluid ;  Clav.  elongata,  from  the  nature  of  the  coral  in  which  it  is  chambered,  could 
not  have  been  living  far  beneath  the  surface  ;  whereas  Clav.  lata  was  dredged  up  from 
a  depth  of  sixty-six  feet.  Any  inferences,  therefore,  as  to  the  state  of  submersion  of  a 
rock  during  the  life  of  the  fossil  species  of  Clavagella  which  there  occur,  should  be  made 
with  caution  by  the  geologist. 
In  conclusion,  it  maybe  observed,  that  though  this  genus  is  now  rare  in  cabinets,  it 
is,  in  all  probability,  widely  diffused  ;  and  collectors  cannot  be  too  astute  in  examining 
masses  of  coral  and  submerged  perforated  rocks,  with  a  view  to  the  further  elucidation 
of  the  habits  and  structure  of  these  interesting  animals. 
PLATE  XXXV. 
Figg.  1,  2.  Tlie  interior  of  the  two  parts  of  Mr.  Goldsmith's  specimen  of  Astraopora, 
containing  two  individuals  of  Clavagella  elongata.  The  several  points 
represented  at  a,  /3,  y,  ^,  come  in  contact  when  the  two  parts  are  placed 
together. 
1.  a.  Anterior  wall  of  the  cavity  in  which  the  larger  individual  is  situated. 
d.  Broken  termination  of  the  posterior  tube  or  siplionic  sheath. 
a.  Anterior  portion  of  the  cavity  of  the  smaller  individual. 
/3.  Portion  of  a  cavity  occupied  by  a  Petricola. 
y.  Anterior  edge  of  the  wall  of  the  coral  chamber. 
^.  A  broken  group  of  Serpula. 
e.  Insulated  shelly  plate,  with  tubular  perforations  at  the  anterior  end  of  the 
ovate  chamber, 
a'.  Fixed  valve  imbedded  in  the  coral. 
2.  a.  Cavity  of  the  smaller  individual. 
+  .  Perforated  shelly  plate  of  the  anterior  ventral  edge. 
VOL.  I.  2  N 
