OF DENISON UNIVERSITY. 
159 
closely related to Ph. constellata, Hall, from the Clinton Group of Can- 
ada. A specimen from Hamilton, Ontario, before me, may be distin- 
guished by the fact that the monticules appear only as slightly elevated 
patches, and the thickness of the frond is reduced to very small dimen- 
sions, perhaps .7 mm, and the frond seems to have been of small size. 
Specimens collected by Prof. N. S. Shaler, however, from Anticosti, 
Canada, show all the features of our Ohio specimens. 
Locality and position. Soldiers’ Home Quarries, Allen’s Quarry, 
Fair Haven, Todd’s Fork, Clinton Group. 
VH. Ph^nopora MAGNA, Hall and Whitfield. 
{Plate XV, Fig. 6 ; Plate XVI, Fig. 2; Plate XVH, Fig. 7.) 
Stictopora magna, Hall and Whitfield, 1875, Ohio, Pal. Vol. II. 
Stictopora compressa, (Van Cleve) Hall, 1883, 12th Indiana Geol. Report. 
Frond beginning with a narrow stipe which is rounded at its ori- 
gin, indicating that its base was articulating, gradually widening, until 
it attains a width of about 6 mm, then branching dichotomously. The 
dichotomous character of the branching is frequently obscured by the 
unequal development of the branches and by the unequal intervals 
between the places at which branching takes place. When 
the specimens exist only as fragments, pieces of fair size may 
sometimes be found which seem to be portions of lengthened, undi- 
vided fronds, and it is very probable that species of this genus have 
been described as unbranched, simply because the material in hand 
was fragmentary. The general appearance of the frond varies, there- 
fore, exceedingly, from a long, scantily branched specimen, to one 
whose numerous branches look like narrow ribbons woven together. 
The angles at which the specimens branch vary exceedingly, from 
small angles of only 10°, in which the bending of the branches for 
even a slight distance is sufficient to make them overlap each other, or 
assume a parallel direction, to angles of 80° or even 90°. The sur- 
face is covered by conspicuous tubercles, usually low, broad, and 
rounded, but sometimes pointed and well defined, with a less regular 
arrangement than in the former species, or even scattered ; about 5 
tubercles usually occupy a length of 9 mm, although this is subject to 
great variation. 
The cell mouths are small, circular, or slightly oval, arranged in 
