ANT>  PHYSIOLOGY  OP  THE  SPONGIAD^. 
329 
Fig.  19.  Aeboeescent  elongo-subspheeo-stellate,  from  Geodia  carinata,  Boweebank, 
MS.,  X 1060  linear : page  308. 
Figs.  20,  21,  22  and  23.  Pileated  cylustdeo-stellate,  in  progressive  stages  of  develop- 
ment, x660  linear:  page  308. 
Compound  Stellate  Spicula. 
Fig.  24.  Attea-uated  eectajstgulated  hexeadiate,  from  Eiiplectella  aspergillum^  Owen  ; 
first  stage  of  development,  exhibiting  only  the  primary  or  axial  radii,  x 90 
linear:  page  309. 
Figs.  25,  26  and  27.  Progressive  degrees  of  development  of  the  secondary  radii  of  the 
same  form  of  spiculum  represented  by  fig.  24,  X 90  linear : page  309. 
Fig.  28.  The  same  spiculum  as  fig.  24,  with  one  secondary  ray  fully  developed,  x 90 
linear:  page  309. 
Fig.  29.  The  same  spiculum  as  fig.  24,  ha\ing  two  secondary  rays  forming  a right  angle 
with  each  other,  fully  developed,  X 90  linear : page  309. 
Fig.  30.  The  same  spiculum  as  fig.  24,  with  two  secondary  rays  developed  in  opposite 
directions,  x90  linear:  page  309. 
Fig.  31.  The  same  spiculum  as  fig.  24,  with  three  secondary  rays  forming  two  right 
angles  with  each  other,  x 90  linear : page  309. 
Fig.  32.  A fully  developed  attenuated  rectangulated  hexradiate  spiculum,  x90  linear: 
page  309. 
Fig.  33.  The  same  form  of  spiculum  as  fig.  32,  with  the  whole  of  the  secondary  radii 
fully  developed,  but  with  one  only  of  the  axial  radii  produced,  x 90  linear : 
page  309. 
Fig.  34.  Slendee  attenuated  eectangulated  hexeadiate,  from  Eiiplectella  aspergillum, 
Owen,  x 90  linear : page  310. 
Fig.  35.  Ctlindeo-eectangulated  hexeadiate,  apically  spined,  from  a specimen  of 
Euplectella  in  the  Museum  of  the  Jardin  des  Plantes,  Paris,  xl30  linear: 
page  310. 
Fig.  36.  One  of  the  radii  of  the  spiculum  represented  by  fig.  35,  exhibiting  the  spination 
of  the  apices,  x 400  linear:  page  310. 
Fig.  37.  Part  of  the  axial  shaft  of  a cylindro-rectangulated  hexradiate  spiculum,  exhi- 
biting the  parts  from  which  the  radii  would  be  produced,  from  the  Euplec- 
tella in  the  Museum  of  the  .Jardin  des  Plantes,  Paris,  x400  linear:  page  310. 
Fig.  38.  Bifuecated  eectangulated  hexeadiate  stellate,  from  the  Euplectella  in  the 
Museum  of  the  Jardin  des  Plantes,  Paris,  xl060  linear:  page  311. 
Fig.  39.  Teifuecated  attenuato-hexeadiate,  from  Euplectella  aspergillum,  Owen,  having 
the  ray  nearest  the  eye  broken  off  at  its  base,  xl060  linear:  page  311. 
2 Y 2 
