REPORT OF THE STATE PALEONTOLOGIST 1901 447 



higher beds enabled Mm to undertake this identification with 

 very satisfactory results. 



Iron pyrites bed at the horizon of the Tully limestone in western 

 New York. Recent investigations of the stratigraphy of the 

 Devonic series in western New York has brought out the fact 

 that, from the point at which the Tully limestone reaches its 

 western extinction close on the eastern shore of Canandaigua 

 lake and from there westward to Lake Erie, its position in the 

 succession of strata is unfailingly marked by a deposit of iron 

 pyrites in the form of a thin sheet an inch or two in thickness^ 

 becoming in places discontinuous and nodular. It proves as re- 

 liable a bench mark in the strata as does the limestone itself^ 

 always maintaining the position of the limestone as the bound- 

 ary formation between the Hamilton shales beneath and the 

 Genesee shales above. This pyrite is usually very compact 

 and hard, and in many places among the twigs, balls and pellets- 

 of evidently concretionary nature are entangled considerable 

 numbers of diminutive fossils. At the meeting of the American 

 association for the advancement of science at Columbus in 1899^ 

 the writer called attention to this peculiar occurrence in the 

 hope of eliciting some expression as to the probable origin of 

 such a continuous deposit of this peculiar nature extending un- 

 broken for almost 100 miles. Considering that the deposit pre- 

 ceded a period of evidently shallow, inclosed coastal areas or 

 embayments, where organic decomposition proceeded in such a 

 manner as to impregnate the muds with bituminous matter 

 (represented in the black shales of the Genesee), it seemed 

 natural to conclude that the environment which conditioned the 

 formation of this iron sulfid was also due to excessive organic 

 decomposition with generous liberation of iron oxids. 



As long ago as 1885 the writer described a considerable num- 

 ber of organisms from this pyrite layer, recognizing the fact 

 that they presented similarities to species of the preceding or 

 Hamilton fauna, but their diminutive form seemed to render 

 actual identification of them with previously known species in- 

 secure, and hence for the most part they were described as new 



