1895.] Sponges: Recent and Fossil. 543 
Devonian, and died out in large, simple or rugose species in 
the lower Carboniferous age. 
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Fic. 6. Cyathophycus. (After Hall.) Fic. 7. Dictyophyton. (After Hall ) 
A variety of sponges occur in deposits of Niagara age in 
* various parts of the world. Among these are some peculiar 
globular and basin-shaped forms that have been found in de- 
posits in Tennessee, in Ohio and in Gotland. They are known 
as Astylospongia, and were free-growing and unattached. The 
spicule are star-shaped and united by their extremities into a 
compact whole. 
One of the most interesting modern discoveries relating to 
fossil sponges is that showing the flint nodules so common in 
all deposits of Cretaceous age, to be formed largely of sponge 
spicules. Not only is this so, but extensive deposits of chert 
of Permian and Carboniferous age, have likewise been shown 
to be made up largely of these bodies. A remarkable paper 
by Dr. G. J. Hinde, describes the contents of a hollow flint, 
about a foot in diameter, from near Norwich, England. He 
gives details of finding, in about three or four ounces of dried 
“ flint meal” from this flint, many hundreds of sponge spic- 
ules, together with remains of other organisms. Some of the 
