Description of new Lower Silurian Sponges. — Ulrich. 245 
remarkable Brachiospongia is from the same horizon. I am 
indebted to Mr. Moritz Fischer, of the geological survey of 
Kentucky, for specimens of this species. 
SACCOSPONGIA DANVIL.LENSIS, n. sp. 
Sponge small, sub-cylindrical, 7 to 12 mm. in diameter ; 
occasionally exhibiting a tendency to bifurcate. Wall vary- 
ing in thickness from 1 to 4 mm. Cloacal cavity variable, 
sometimes small, at other times comparatively large. Outer 
surface rough, in the worn or greatly compressed condition 
appearing as though traversed by small interrupted longitu- 
dinal ridges. Canal-apertures more or, less oblique, small, 
averaging about 0.6 mm. in diameter, and from 3 to 5 in the 
space of 3 mm. 
This species resembles Heterospongia but an examination 
of the fractured ends of the examples revealed the presence of 
a cloacal cavity. It is a smaller sponge than S. rudis^ from 
which it is distinguished further by its smaller canals. 
Formation and locality : From the siliceous beds at the 
top of the Trenton, at localities in Boyle, Mercer, Franklin 
and Fayette counties, Kentucky. 
DYSTACTOSPONGIA MINIMA, n. sp. 
This name is proposed for a small parasitic sponge appar- 
ently congeneric with D. insolens S. A. Miller. It forms thin 
crusts or small irregular masses upon bryozoa and other 
foreign bodies. The largest seen is about 15 mm. wide and 
5 mm. high at the center. The canals are much smaller than 
in any of the other species and the partitions exceedingly 
thin. About 5 canals occur in 2 mm. The whole skeleton is 
usually replaced by a brown oxide of iron. 
It is doubtful whether the specimens catalogued by me under 
the name Streptospongia confusa Ulrich (Catal. foss. Cin. gr. 
1880) are specifically distinct from Miller's D. insolens. (Jour. 
Cin. Soc. Nat. Hist. vol. v, 1882). The typical examples of his 
species are large amorphous masses, while the specimens 
named by me as above are small and generally attached to ra- 
mose or frondescent bryozoa. Mr. Miller believes them to be 
distinct but I am very much inclined to doubt the propriety 
of separating them as I have failed to note any difference in 
the size and arrangement of the canals between those of the 
large and small examples. On the other hand, the specimens 
now named D. minima differ decidedly from that species in 
