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IOWA ACADEMY OF SCIENCE Voi, XXIX, 1922 
cally outside of the New York Chemung. There are a few doubt- 
ful ancestors of Ordovician age and a derelict or two from the 
Silurian, one from New York and one from England. The 
Cyathodictya oblonga of this paper adds another of Silurian age. 
The Mississippian record is more remarkable for the wide dis- 
tribution of the few forms known than for populous colonies 
such as inhabited Upper Devonian beds ; the Burlington limestone 
species mentioned above was found in Iowa and up to the present 
paper was the only glass-sponge ever reported from the” state. 
The Jurassic and Cretaceous have yielded some more or less 
obscure species. Since the Cretaceous, as well as during most of 
the epochs before then, the glass-sponges have occupied the deeper 
waters beyond the continental shelves. For the facinating his- 
tory of the glass-sponges the reader is referred to an article by 
Doctor John M. Clarke 1 which appeared recently. For detailed 
descriptions and beautiful illustrations access should be had to a 
monograph on them by James Hall in collaboration with Doctor 
Clarke 2 . 
The occurrence of two new species, one of them belonging to 
a new genus, in the Paleozoic rocks of Iowa is here offered as 
a brief contribution to the subject. The first of these belongs to 
one of the more primitive stocks of the glass-sponges which 
Clarke assigns to the genus Cyathodictya. The other does not 
belong to any of the described genera but is nearest, perhaps, to 
the general type of Ceratodictya. Both apparently are Lyssacine 
hexactinellids and are placed in the family Dictyospongidae. 
CYATHODICTYA OBLONGA n. s. 
Plate I, Figs. 1, 4 
Species based on a single elongate, obconic specimen which is 
attached by one side to a block of buff-colored, compact, and 
finely crystalline dolomite. The reticulum is preserved as fine 
linear impressions or casts over the entire surface. The aperlure 
is concealed by the matrix and the body is somewhat flattened 
toward the upper end. The sponge expands gradually for about 
one-third its length above which the sides are nearly parallel until 
just before reaching the aperture where there is a slight but 
appreciable tapering. The pattern of the reticulation consists of 
1 The Great Glass-Sponge Colonies of the Devonian: their Origin, Rise, and 
Disappearance. Jour. Geol, vol. 28, pp. 25-37; 1920. 
2 A Memoir on the Paleozoic Reticulate Sponges constituting the Family Dictyo- 
spongidae. Albany, 1898. 
