OF DENISON UNIVERSITY. 
73 
On the 7 'everse the branches and dissepiments are evenly rounded 
and faintly striated. 
In the frequent bifurcations of the branches, widely separated dis- 
sepiments and general aspect of the zoarium, this species approaches 
Thamniscus, King, and I am inclined to believe that when this group 
of species, to which P, gi^acilis^ Prout, also belongs, is better under- 
stood, they will be removed from Polypora. In my Illinois work on 
the bryozoa I have already placed several species of this type with 
Thamniscus, having been able to show that T. dubius, Schlotheim, the 
type of the genus, also, (at least occasionally) has some of the branch- 
es united by dissepiments. Much study and an abundance of material 
is required before a final disposal of these peculiar species is possible. 
Taking all its characters into consideration, P. impressa is not 
likely to be confounded with any other species known to me. Similar 
impressions behind the zooecia apertures are present in the Upper 
Carboniferous Thamniscus octonarius, UL* This character is one of 
rare occurence among palaeozoic bryozoa and brings some of the meso- 
zoic and recent forms to mind. 
Formation and locality : — Cuyahoga shale of the Waverly series, 
between 50 and 100 feet below the Carboniferous conglomerate, at 
Richfield, Summit Co., Ohio. The type specimen is attached to the 
surface of a small fragment of a ferruginous clay nodule, less than two 
inches square. With it are more or less fragmentary remains of at 
least seven other species of bryozoa. 
POLYPORA GRACILIS, Piout. 
Polypora gracilis, Prout, i860. Trans. St. Louis Acad. Sci. vol. I, p. 580. 
“ “ Prout, 1866, Geol. Surv. 111 . vol. II, p. 422, pi. XXI, figs, i, la. 
“ “ Ulrich, Ibid. vol. VIII, pi. LXI, figs. 10, loa (Now in press.) 
Two specimens, one from Richfield, the other from Sciotoville, 
are provisionally referred to this species. The first shows only the re- 
verse, while the second is an illy preserved mould of the obverse. 
There is, therefore, no certainty that they belong to P. gracilis, 
especially since there are several distinct species of this type in the 
Burlington and Keokuk limestones. 
