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, Gryphaeus, 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 



