Description of new Lower Silurian Sponges. — Ulrich. 247 
0.5 mm. in diameter ; averaging about thirty in a space 
10 mm. square. Their course is nearly always straight but 
the angle at which they pass through the sponge wa 
greatly. Occasionally they may divide. 
A careless observer might mistake this sponge for the shell 
of an Endoceras or perhaps Orthoceras^ to which the form and 
obscure annulations give it some resemblance. However, un- 
usually acute powers of discrimination are not required to see 
that it is a very different organism. 
CYLINDROCCELIA COVINGTONENSIS, n. sp. 
To this species I refer six examples, two of them doubtfully, 
all derived from the middle beds of the Cincinnati group at 
Covington, Ky. The skeleton in all of them has been changed 
to crystalline calcite without, however, destroying the canals. 
Three of them are sub-cylindrical fragments of which the 
largest affords the following measurements : length 45 mm. ; 
diameter of lower extremity 25 mm. ; diameter of upper end 
32 mm. ; diameter of cloaca at lower end 6 mm. ; diameter of 
same at upper end 22 mm. ; thickness of sponge wall at lower 
extremity from 9 to 10 mm. ; thickness of same at upper end 
from 3 to 6 mm. ; canals mostly 1.5 mm. in diameter, but 
varying from 0.5 to 2.5 mm., with an average of eight in 10 
mm. square. 
In all but the two doubtful specimens, the canals penetrate 
the sponge wall in a remarkably irregular manner, all direc- 
tions being pursued by them. When the dermal layer is pre- 
served the surface appears smooth with here and there a canal 
aperture. 
Two of the cylindrical fragments are smaller, taper less rap- 
idly, and have a narrower cloaca than the third specimen from 
which the above measurements were taken and which is con- 
sidered the type. These specimens approach the Minnesota 
species next described. Another I believe to be the basal por- 
tion of the sponge. This is of conical shape, about 50 mm. in 
length, tapering from a diameter of 24 mm. to a point. The 
upper end, which I have ground and polished, exhibits num- 
erous irregular canals but no evidence of the cloaca. The two 
doubtful specimens are also of conical shape, but both have a 
deep cup and are smaller. It is possible that these may repre- 
sent a different species but, provisionally, I prefer to regard 
them as young examples of C. covingto7iensis. 
