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ORS GE, OT Oe RIE SE 
ae Se Ee eee ae a ee SE Ae SARA ee oe gO See ee ee SRE ee ee ee. ee 
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Fossils in Rensselaer County, N. Y. 205 
leaning to the northwest; and, as a result of this arrangement, 
the rocks of this region have a nearly uniform southeasterly 
dip. I was unable to obtain any fossils in these rocks, but at 
a locality about half a mile eastward of the first exposures 
examined I was more successful. At this point an apparently 
higher series of slates is met with, and these are, in turn, suc- 
ceeded by a considerable deposit of conglomerate limestone. 
This latter rock is a most singular formation, g tania as if 
composed of innumerable blocks and wedges of limestone con- 
fusedly thrown down and iitenwatd firmly Stren together. 
It appears almost incredible, at first sight, that fossils should 
occur in such a looking mass. But in a detached block of 
main mass an “aheqatvoel specimen of Hyolithes sneenen 
Billings; and on ex amining, on my return home, a e also 
uve from the rock in situ b y Mr. Bell, I found a spectdiaks 
of the ce nhc ed by me under the name of Oboleila 
nitida. All these species likewise occur in the Lower 
Potsdam fimestones at ‘Troy. No perfect oo of the 
around.* The surface of the ats is finely granular. On 
page 405 of his “ Paleozoic Fossils,” vol. i, Mr. Billings has 
figured] the pygidium of a trilobite from the Quebec group, 
¢ i i i sam 
which has the ate rim notched in precisely the e 
manner as that of C. trilin Mr. Billings does not refer it 
positively to an nus. On comparing the characters fur- 
gen tes. 
able that it is a tail piece ‘of Conoe phat alites Zenkeri, describ 
on page 898 of Mr. at work cited. 
* In the configuration of the border above noticed, this species differs widely 
from any species of the genus hitherto described. Barrande, in his beautiful 
Work on the Trilobites, places the genus Coniemhalbten in his group of genera in 
which the border of the igen is unbroken or entire (Systéme Silurian de la 
héme, vol. i, p. 220). e species known as Conocephalites Iowensis, from the 
Wisconsin Primordial et Gerakbes another exception to the rule. In that species 
(leh her oh a pygidium i is prolonged backward into two long diverging spines. 
