Notes . 
632 
colonisation, and immediately behind it nothing but compact 
masses of life, and even if it should sail by accident far back 
over the healthy inhabitants, it would in all probability only come 
to those suffering more and more from suffocation and decompo- 
sition the farther it went (but even should it so happen at any time 
that it should travel so far towards the centre of the circle as to 
reach a place where its ancestors had been completely buried and 
start there a colony, it would only perform overagain what the first 
sponge had done and what I have attempted to describe, and so 
form the second layer of sponges) ; therefore it must naturally 
develop in the direction of the unencumbered surface. 
“ Thus this ring of life would pass over the bottom of the sea, 
to be followed by another ring from another source, after an epoch 
of uninterrupted chalk deposition, or may be the same life would 
return after a tour in other seas. 
“ Thus it is possible that, in the past and the future, wave 
after wave of sponge life may pass over the ocean floors whose 
existence may be registered in stone by the separation of the 
small quantity of silica contained in the nacre of the Foramini- 
fera. — A. Anthony Nesbit.” 
(In borrowing the above notice from our contemporary, “ Land 
and Water,” we wish to bespeak for it the attention of our geo- 
logical readers. — E d. J. S.) 
Erratum.— P age 553, line 22, for “adult” read “earlier.” 
