246 Description of new Lower Silurian Sponges. — Ulrich. 
Type : C- endoceroidea^ n. sp. 
Sponges of this genus are liable to confusion with slightly 
tapering forma of Orthoceras and Etidoceras. The absence of 
septa and presence of canals should, of course, distinguish 
them at once. 
The specimens of two of the species are now siliceous, that 
being the usual conditions of the fossils associated with them 
in their respective beds. In these the canal system is pre- 
served in a satisfactory manner, but it is very difficult, if not 
impossible, to make out the minute details of structure. 
Those of the other two species now consist of rather coarsely 
crystalline calcite in which even the canals are not readily de- 
terminable, much less the spicule fibers. Under these adverse 
circumstances the systematic position of CylindroccElia can- 
not be established with any degree of certainty, and my refer- 
ence of the genus to the Calclspongke is, therefore, only 
provisional. 
CYLINDROCCELIA ENDOCEBOIDEA. n. sp. 
Of this species my collection affords but a single partly silic- 
ified example which I found at High Bridge, K3^, in the Birds- 
eye limestone which at that locality forms the top of the Ken- 
tucky river gorge. It is incomplete at the lower end, tapers 
slowly, 170 mm. long, 45 mm. in diameter at the upper end, 
and 32 mm. at the lower extremity. At the lower end the 
cloaca is about 10 mm. in diameter and the sponge wall varies 
in thickness between 9 and 13 mm. The specimen is broken 
across at a point about 80 mm. from the top. Here the cloaca 
is 17 mm. in diameter and the wall about 12 mm. thick. At 
the upper extremity the wall is much thinner and is now nar- 
rowly rounded. Originally it may have formed a sharp eflge. 
On one side the outer surface exhibits obscure transverse un- 
dulations. 
Where the outer surface appears best preserved but few 
canal apertures are shown, but where the surface is ground or 
a fragment chipped away and moisture applied, a much larger 
number are disclosed. From this it is evident that a thin dermal 
layer was stretched over the surface through which but few of 
the canals penetrated. A similar layer was developed on the 
inner or cloacal surface. 
Canals numerous, sub-circular in cross-section, of var- 
iable size, the largest about 1.5 mm. the smallest less than 
