36 — oS. W. Ford—Primordial Fossils of New York. 
topography of the region. Commencing at Schodack eis 
in Rensselaer County, they may be traced southward, 
slight interruptions, along the east shore of the Hudson ‘River, 
for nearly three miles; and for a goodly portion of this dis- 
tance they are finely displayed. In some instances they con- 
stitute bare, natural cliffs, more than a hundred feet in height. 
They may be studied to good advantage in a number of places, 
but one of the best points is in the “old quarries a short dis- 
tance north of a line running due eastward from Mr. Peter 
McCabe’s ice-house. At this point I was enabled to obtain the 
following measured section, which will, I think, be found in 
the main correct. e strata are enumerated in ascending 
order, or, as they are met with in passing from the Hotee 
River Railroad track upward. 
SEcTION. 
Po AEMISEORY WAG oo ct ae eles SWas 80 feet. 
2. Dark blue, compact limestone, in regular 
courses, with slight shaly partings .-_.--- be ed 
my peedmn. GuaIte TOOK. oo 1 foot. 
4, Green calcareous slate 2-22.22. oe 6 inches. 
P; Reeadise Oteree PO0K 2 i ae ie ec ok at agg 
6. Green calcareous slate... 22 --- 22 oe 10 feet. 
iy & cars ras <pihse limestone becoming brecciated 
ce 
8. Michdeeray slate, say ..-....- ad 
Potal thickness about 2... ..2...-.5..c2 120 feet. 
All of the above mentioned beds succeed one another con- 
formably, and all belong, with but little doubt, to one and the 
same physical group. e fossils obtained from them prove 
that they belong to the Primordial zone, and to that division 
of it known as the ets Potsdam. The paleontological evi- 
dence in detail is as follow 
From the limestone depueil near the top of the escarpment 
(No. 7 of the section) I have thus far obtained the following 
eleven species: Paledphychus incipiens, ella crassa, o- 
theca rugosa, Hyolithes ener canus, H. impar, Hyolithellus 
micans, Microdiscus lobatus, M. speciosus, Seiad trilineata, 
yecmtsiny asaphoides and Fordilia T Troyenets 
m the dark blue flinty limestones a short coat below 
(No. 2 of the 2 a I have obtained but a single species, the — 
Microdiscus 
EPe 
The slate deposit (No. 1) is likewise fossiliferous, but I have _ 
not yet found opportunity to minutely examine it. From a — 
soigeesd oe a occurring within a short distance of its visible _ 
tase: ever, I have obtained a specimen which appears to 
me to res most likely a shell of the Pteropod species Hyolithellus 
a 
