APPENDIX. 419 



have been the boundary of thfi lake for any length of time ; 

 and it really seems, from many accounts, that the water 

 ef the Niagara once run off to the southward. 



CLASSIFICATION OF MARINE RELICKS. 



I insert, on account of its peculiar importance, the fol- 

 lowing classification of the fossil shells of the United 

 States, by my friend John G. Bogert, Esq. 



Pectinite, #rca, Glycemeris, Jinomla Vitrea> Ostrcea Fascinata^ 



Terebratulites. 



These specimens I chiseled out of the summit of a 

 high limestone hill, in the County of Columbia, about 

 300 feet above the surface of the Hudson river, and dis- 

 tant four miles from the river, and 130 from New-York. 



The limestone in this neighbourhood, at that distance 

 above the level of the river, abounds with specimens of 

 this description, and extends along the edge of the sum- 

 mit several miles, and not more than about five feet in 

 breadth on the southeasterly side ; none appearing on 

 the northwest side near the Hudson. 



That part of the hill from which I procured these spe- 

 cimens, presents a perpendicular of about 80 feet from its 

 base ; although from the base of the perpendicular to the 

 stream or river below, there appears to be a descent of 

 at least 70 feet. 



If we take a view of this tract of country, extending 

 from within four miles of the Hudson to Hillsdale on the 

 Taconick mountains, in the State of Massachusetts, where 

 I found similar specimens; a geological mipd cannot be 



