HAMILTON GROUP. 
157 
On both sides of Otsego lake, the same shale appears in numerous points, and abounds 
with fossils, among which we find the Ridged posidonia, Mucronated delthyris, Concentric 
atrypa, Keeled atrypa, Cryphaeus, etc. 
On the road from Cooperstown to Burlington, are some small points of interest, one of 
which is near the summit elevation about three miles from the latter village. There the first 
impression of a plant was found, in the ascending order of the New-York System, whose exter¬ 
nal markings or structure resembled those of terrene origin ; a fact of no small importance in 
the history of such plants. The same kind were subsequently seen with Mr. Mather on the 
road from Summit to Hinsdale, in the first district, where they are comparatively in conside¬ 
rable abundance. A good specimen was also picked up in a quarry near the forks of the 
Unadilla. The wood-cut below gives but an imperfect idea of it. The plant shows about 
three small protuberances of a lentiform shape, placed nearly side by side, 
38. 
In Madison county, the greatest exposition of this group is in the neighborhood of West- 
Hamilton village ; various openings having been made in the hill back of the Seminary, from 
the bottom to the top. The lower part of the hill shows irregular layers of sandstone and 
shale, the former in less quantity; above which are coarse shales of different kinds, extending to 
near the top of the hill. Back of the Institution, at a little higher level, the shale which was 
quarried has fallen into fragments. At the top of the hill, about twenty feet of sandstone and 
shale are exposed, a considerable quantity of stone and refuse having been thrown out. 
Fossils are numerous at the quarry, among which are the Mucronated delthyris, the one 
