CHAP. X.] CONTINUITY OF THE CHALK. 485 
of ‘spicules of the sarcode,’ one large, C-shaped, the 
other much more minute, answering to Bowerbank’s 
‘tridentate equianchorate’ type; every now and then 
Fic. 82.—Ventriculites simplex, TouLMIN Smirn. Section of the outer wall, showing the 
structure of the silicious network. (x. 50.) 
the rind thus formed coming to the margin of a small 
pore. The interior of the sphere is filled with soft 
semi-fluid sarcode, supported by the loosest possibie 
Fic. 83.—Celosphera tubifex, WYVILLE THoMson. Slightly enlarged. Off the coast of Portugal. 
mesh-work of granular horny matter and_pin- 
headed spicules. From points apparently irregularly 
placed on the surface of the sponge, tubes about 
3 mm. in diameter run out in all directions; 
the walls of the tubes are thin and delicate, being 
