BULLETIN OF THE LABORATORIES 
174 
XXL Callopora Ohioensis, sp. n. 
{Plate XVI, Fig. 6; Plate XVII, Fig. 17.) 
Zoaria more regular in formation than the two species last de- 
scribed, branches varying from 2.5 mm, to 5 mm. in diameter. Cells 
apparently of two kinds. The true cells are of nearly uniform size, 
subcircular, and stationed apart at somewhat regular intervals, from ii 
to 13 occupying a distance of 3 mm. Separating these cells and 
usually completely isolating them are a number of interstitial cells very 
variable in size, even in the same part of the branch, some being lar- 
ger and some smaller than the true cells, but usually of the same aver- 
age size. The true cells are usually in our specimens filled more or less 
with sediment and so are more readily distinguishable. Tangential sec- 
tions show this feature very plainly. Longitudinal sections do not 
show any difierence in size between the true and the interstitial cells, 
nor is there any appreciable difference in the number of the straight 
diaphragms; these features will distinguish it readily from C. elegantu- 
la, Hall. It will be remembered that only under favorable circum- 
stances was any difference noted in the number of diaphragms in the 
last species. The number of diaphragms in general is but slightly greater 
than in that species. 
Locality and position. Centreville, Clinton Group. 
PLATE XV. 
Fig. I. Phylloporina angulata, Hall ; the small form for which the name P. 
Daytonensis was suggested by Hall and Whitfield. 
Pig. 2. Heminypa Ulrichi. n. sp ; a part of a frond showing the infundibuli- 
form structure. 
Pig. 3. Clathropora frondosa, Hall ; a part of a frond showing the point 
of articulation with some basal structure. 
Fig. 4. Clathropoi'a Clintonensis, Hall and Whitfield ; fragment of a frond 
showing a somewhat similar provision for articulation. 
Fig. 5. Ptilodictya expanse., Hall and Whitfield ; a part of a typical frond 
from Todd’s Fork, Clinton County. 
Fig. 6. Phcenopom niagna, Hall and Whitfield; a fragment showing the sur- 
face. 
