OF DENISON UNIVERSITY. 
lOI 
VIL Calymene Bliimenbachii ? . . . Brongniart. 
VIII. Lichas breviceps, ..... Hall. 
IX. Arionelliis ? , ..... 
X. Dalmanites Werthneri, . . . . n. sp. 
The trilobites so far studied seem to be either identical with, or 
closely related to Niagara forms. Hall and Whitfield, in their de- 
scription of Illcejius Daytonensis, say that “specimenshaving the same 
features have been collected from the Niagara Group of Wisconsin and 
Illinois.’’ I. Madisonianus is found in Wisconsin; however, I am 
unwilling to consider this as good evidence, since the identification is 
based upon one specimen, and that, the pygidium. /. ambiguus 
finds a close relation in /. insignis, a typical, western Niagara fossil. 
Lichas breviceps agrees quite closely in all important characteristics, es- 
pecially those of the pygidium, with described forms of this species 
from Waldron, Indiana. Dalmanites PVert/meri is closely related to 
D. vigilans and D. verrucosus, also from the Niagara strata of Indiana. 
Of the other species not much can be said in the present state of 
knowledge concerning them. 
GENUS ACIDASPIS, Murchison. 
I. Acidaspis . 
{Plate XIII, Fig. 23.)- 
A fragment of a trilobite belonging to this genus has been found, 
presenting chiefly the movable cheek, but also portions of the glabella. 
Glabella poorly preserved; including the occipital regions its 
breadth, as nearly as can be determined, is equal to about one third or 
two fifths its length, the widest part being behind the middle, between 
the eyes ; lateral lobes apparently three on each side, the middle and 
posterior lateral lobes along one side of the glabella being distinctly 
defined in the specimen, the third, anterior lobe, less plainly, on ac- 
count of the imperfect preservation of the fossil at this point. Lat- 
eral lobes of an almost oval outline, directed obliquely forward and 
outward, the posterior one larger than the middle lobe, separated by a 
distinct furrow from the cheeks and from themselves ; there is a broad 
groove between the lateral lobes and the glabella proper, in addition to 
which the furrow between the middle and posterior lateral lobes and the 
occipital furrow rounding behind the posterior lateral lobe bend 
