290 
DE.  J.  S.  BOWEEBAXK  OX  THE  AXAT03IT 
an  attenuated  spiculum  from  PacJiymatisma  Jolmstonia,  and  Plate  XXIII.  fig.  43,  a 
cylindro-ternate  spiculum  from  the  same  sponge. 
Patento-teenate. — Having  the  terminating  radii  disposed  at,  or  nearly  at  right  angles 
to  the  shaft  of  the  spiculum,  the  curves  of  the  radii  being  usually  more  or  less  inclined 
back’wards  towards  the  base  of  the  shaft.  Plate  XXIII.  fig.  44,  represents  a spiculum 
from  Geodia  IPAndrewii,  Bowekbank,  MS.  A new  species  from  Yigten  Island,  coast 
of  Norway. 
Paten  to-  and  expando-ternate  spicula  are  both  subject  to  variations  dependent  on  the 
form  of  the  shaft,  which  in  some  cases  is  attenuated  from  the  apex  to  the  base,  where  it 
terminates  acutely ; or  the  shaft  is  cyhndrical,  subfusiform  or  spinulate : in  such  cases,  we 
should  designate  them  as  spinulo-expando-ternate,  or  otherwise,  as  might  be  requisite  for 
accurate  distinction  of  the  form. 
Recuevo-teenate. — The  terminating  radii,  recurved  from  about  100  to  140  degrees 
from  the  apical  line  of  the  axis  of  the  shaft.  The  curves  of  the  radii  are  always  more 
or  less  inclined  towards  the  base  of  the  shaft  of  the  spiculum  (Plate  XXIII.  fig.  45). 
From  Geodia  Barretti,  Boweebank,  MS.  Vigten  Island,  Norway. 
Fuecated  attenuato-patexto-teenate. — The  radii  of  the  ternate  apex  is  not  always 
simple ; in  some  species,  as  in  Pachymatisma  Listen,  Boweebajsx,  MS.,  a new  species 
from  Madeira,  and  in  Geodia  Barretti,  Boweebank,  MS.,  from  Vigten  Island,  Norway, 
each  of  the  rays  have  bifurcated  terminations  in  the  same  plane  as  the  primary  radii,  as 
represented  in  Plate  XXIII.  figs.  46  and  47,  the  former  being  erect,  and  the  latter 
having  the  plane  of  the  radii  presented  to  the  eye.  From  P.  lAsteri,  Boweebaxk,  MS. 
Spiculated  dichotomo-patento-teexate  (Plate  XXIII.  fig.  48),  is  a stiU  more  com- 
plicated form,  the  radii  of  the  bifurcations  each  terminating  again  dichotomously ; but 
the  secondary  bifurcations  are  not  all  of  them  in  the  same  plane  as  the  primary  ones,  a 
portion  of  them  being  at  right  angles  to  it,  and  the  shaft  is  also  carried  through  the 
common  central  base  of  the  whole,  giving  it  a spiculated  form,  as  represented  in  the 
figure.  This  prolongation  of  the  shaft  through  the  common  base  of  the  radii  of  the 
ternate  spicula  is  not  confined  to  the  one  described  above,  but  it  does  not  appear  to  be 
a normal  form. 
I have  never  seen  a quaternate  spiculum  associated  with  the  connecting  spicula,  in 
which  all  the  radii  were  equi-divergent ; in  all  such  cases  three  appear  to  represent  the 
ternate  type  of  spiculum,  and  the  fourth,  or  supplemental  one,  is  a continuation  of  the 
axial  line  of  the  shaft,  which  passes  through  the  united  bases  of  the  ternate  portion  of 
the  spiculum.  I have  therefore  designated  these  forms  as  spiculated  ternate  rather  than 
quaternate. 
These  spicula  are  rather  anomalous  in  their  character.  They  frequently,  but  not 
universally,  accompany  the  true  connecting  spicula;  the  ternate  apices  do  not  usually 
reach  the  under  surface  of  the  crustated  coat;  in  Geodia  Barretti  and  some  other 
species,  in  which  they  occur  but  occasionally,  they  partially  fulfil  the  office  of  con- 
necting spicula.  There  is  a constant  and  striking  difference  in  the  proportions  of  the 
