AND  PHYSIOLOGY  OP  THE  SPONGIADiE. 
325 
Fig,  49,  Spiculated  poeeecto-teenate,  from  GeodiaM'Andrewii,  Boweebank,  MS,,  X 90 
linear:  page  291, 
Fig,  50,  Spiculated  eecuevo-teenate,  from  Geodia  Barretti,  Boweebank,  MS,,  x 90 
linear:  page  291, 
Fig,  51,  Spiculated  eecuevo-teenate,  having  the  spiculate  ray  deflected  from  the  axial 
line,  from  Geodia  Barrefti,  x90  hnear:  page  291, 
Fig,  52,  Eecuevo-teenate,  having  one  of  the  rays  distorted  upwards,  from  Geodia 
Barretti,  x 90  linear:  page  291*. 
Prehensile  Bpicula. 
Fig.  53.  Apically  spined  eecuevo-quateenate,  from  Euplectella  cucumer,  Owen,  x 90 
linear:  page  291. 
PLATE  XXIV. 
Defensive  Spicula. 
Fig.  1.  Attenuato-acuate.  entieely  spined,  from  Dictyocylindrus  ventilahnmi^  Bowee- 
bank, MS.,  X 260  linear:  page  293. 
Fig.  2.  Acuate,  entieely  and  veeticillately  spined,  from  an  undescribed  sponge, 
X 400  linear:  page  293. 
Fig.  3,  Cylindeical,  entieely  and  veeticillately  spined.  Sponge  unknown,  x 400 
linear:  page  293. 
Fig.  4.  Spinulo-eecuevo-quateenate,  first  stage  of  development,  x 130  linear:  page  294. 
Fig.  5.  The  same  spiculum  as  fig.  4 in  the  second  stage  of  development,  Xl30  linear: 
page  294. 
Fig.  6.  The  same  spiculum  as  fig.  4 in  the  third  stage  of  development,  Xl30  linear; 
page  294. 
Fig.  7.  The  same  spiculum  as  represented  by  fig.  4,  but  in  a completely  developed  state. 
Sponge  undescribed,  x 130  linear:  page  294. 
Fig.  8.  Fusifoemi-poeeecto-teenate,  a very  early  stage  of  development,  from  Tetheci 
cranium,  Johnston,  x660  Linear:  page  295. 
Fig.  9.  A further  stage  of  development  of  a fusiformi-porrecto-ternate  spiculum  from 
Tethea  cranium,  x260  linear:  page  295. 
Fig.  10.  An  adult  fusiformi-porrecto-ternate  spiculum  from  Tethea  cranium,  X 160  linear : 
pages  289  and  295. 
Fig.  11.  A fusiformi-porrecto-ternate  spiculum  from  Tethea  cranium,  charred  to  exhibit 
the  cavities  of  the  shaft  and  radii,  x260  linear:  page  295. 
Fig.  12.  Fusifoemi-eecuevo-teenate  spiculum,  in  an  early  stage  of  development,  from 
Tethea  cranium,  Johnston,  x260  linear:'  page  295. 
* The  number  of  the  figure  in  page  291  is  erroneously  printed  53  instead  of  52, 
