New York State Museum 



VALUE OF AMMGEMA AS AN INDICATOR OF FRESH- 

 WATER DEPOSITS 



DURING THE 



DEVONIC OF NEW YORK, IRELAND AND THE 



RHINELAND 



BY JOHN M. CLARKE 

 PI. 11 



In 1842 Vanuxem described, from Mount Upton N. Y., as 

 Cypricardites catski lien sis and 0. a n g u s t a t a , 

 certain fossil clams, for which Hall at a later date erected the 

 generic term Amnigenia, including both form® under the 

 single name A. catskillensis. Neither Vanuxem nor 

 Hall ventured to suggest that this organism was closely related 

 to the existing fresh-water claims Anodonta, or Unio, but 

 this proposition has at various times been made without close 

 analysis of its probabilities; more recently, however, it has been 

 carefully discussed by Beushausen. 1 



The exterior resemblance of this mollusk to Anodonta is 

 certainly most striking, but this fact contributes less to the 

 indication of its fresh-water habit than the conditions under 

 which its involving sediments were laid down. This clam has 

 been found not only at Mount Upton, the original locality, but 

 also, according to Prof. Hall, at " Gilbertsville, Otsego co.; on 

 the road from Jefferson to Gilboa, and at the base of the hills 

 to the south of Jefferson, Schoharie co. N. Y. Prof. J. J. Steven- 

 son has found a single valve of this fossil in the Catskill red 

 sandstone on Wills creek, about 1 mile from Hyndman, and 1600 

 feet above the base of the formation, in Bedford co. Pa." More 

 recently it has been found in quantity and well preserved at 

 Oxford, Chenango co. in the quarries of the F. G. Clarke blue- 

 stone co. Its occurrence in New York is, so far as known, 

 restricted to the Oneonta sandstone, the origin and stratigraphic 



i Jahrb. d. kotiig. preuss. geol. Landesanstalt fur 1890. separat p. 1-10, 1891. 



