Raymond : Thk Ciiazv Formation and its Fauna. 499 



Accordingly it was necessary first to undertal<e a revision of the 

 Chazy fossils and this work constitutes the bulkier part of the i)resent 

 series of articles. 



The collections on which this study is based have been made during 

 the last five field seasons, first for the writer's private collections and 

 later for the Cornell, Yale, and Carnegie Museums. Field work has 

 been carried on in the Lake Champlain region, the Ottawa ^'alley, the 

 Mohawk Valley, Central Kentucky, Eastern Tennessee, and Minne- 

 sota, and for opportunity to do this work 1 have been especially in- 

 debted to Professor Gilbert D. Harris, of Cornell, and to the late 

 Professor C. E. Beecher, of Yale. For other favors in connection 

 with this work I am indebted to several gentlemen and to them I have 

 expressed my obligations in the body of the paper. My thanks are 

 due Professor Charles Schuchert, who has read the manuscript and 

 made many valuable suggestions. To Professor George H. Hudson, 

 of Plattsburgh Normal School, I am indebted for valuable assistance 

 in the field and for some of the i)hotographs which illustrate this 

 article. 



Distribution of the Chazv Formation. 



The Chazy formation was named by Ebenezer Emmons (Final Re- 

 port, Geology, New York, 1842) from the outcrops studied by him 

 at Chazy Village, New York, and so that locality becomes typical for 

 the formation. 



In stratigraphic position the Chazy overlies the Beekmantown 

 (formerly known as Calciferous), and underlies the Lowville (formerly 

 known as Birdseye) , a member of the Mohawkian. The Chazy forma- 

 tion may be traced from Chazy north and south along the Champlain 

 Valley from Orwell, Vermont, to Joliette, north of Montreal, and north- 

 west along the Ottawa \'a]ley to .VUumette Island, eighty miles north- 

 west of Ottawa. The formation has been detected again at the Mingan 

 Islands in the Gulf of St. Eawrence, where it covers a small area. 



In the region of Lake Chami)lain the strata of the formation are mostly 

 limestone and the thickness ranges from 60 feet at Orwell to 890 feet 

 at Valcour Island. Further north the thickness is not definitely known. 

 In the region of the Ottawa Valley the forniation is usually 100 to 200 

 feet in thickness and is about half limestone and half sandstone, the 

 limestone usually overlying the sandstone. At the Mingan Islands 

 the thickness of the formation is estimated at zoo feet and the strata 



