A84 THE DEPTHS OF THE SEA. ' [erap. x, 
such recent forms as Aphrocallistes, Iphiteon, Hol- 
tenia, and Askonema with certain series of the chalk 
Ventriculites, there cannot be the slightest doubt that 
they belong to the same family—in some cases to 
very nearly allied genera. Fig. 80 represents a very 
beautiful specimen of Ventriculites simplex preserved 
in flint, for which I am indebted to Mr. Sanderson of 
Edinburgh. Looking at this in the light of our 
knowledge of Huplectella or Aphrocuallistes beatriz, 
we have no difficulty in working out its structure, 
even to the most minute microscopic detail. 
Other sponges, belonging chiefly to the Lithistidee 
and the Corticatze, re- 
produce with wonderful 
accuracy the more irre- 
gular sponge-forms of 
the chalk and _ green- 
sand; and a group, as 
yet undescribed, but 
apparently an aberrant 
family of the Esperiade, 
send out long delicate 
a Pocono ees eee ee ee 
shghtly, but in a most 
characteristic way, at the point of their insertion 
into the sponge body, recalling very forcibly the 
peculiar manner in which the tube-like root processes 
join the sponge in such genera as the vaguely defined 
Choanites. 
One sponge belonging to the group is represented 
at Fig. 838. A sphere 15 to 20 mm. in diameter con- 
sists of a smooth glossy external rind, composed of 
closely meshed pin-headed spicules, with two kinds 
be Sh VV 
The. 
IH 
&( A) 
