RaViMOXD: TllK CHAZY I'OKMAIKIX AND ITS FaUNA. 525 



Camarotivchia plena r, Leperditia canadensis c. 



Isotclus /larrisi c, 



D.^,. Covered to point on which the Lowville and Black River 

 limestones are exposed. 



/Remarks on tJie l^a/conr Is/and Sections. 



Correlation of Sections. — The section on the south end of Valcour 

 Island (Section A) does not extend to the top of the formation and 

 it is therefore necessary to supplement it with sections taken on the 

 north end of the island where the upper beds are well exposed. Sec- 

 tion I) begins in the middle Chazy and extends through the whole 

 up|)er Chazy, but a large part of the strata are covered. Section C is 

 a short one, but exhibits about thirty-five feet of the upper beds not 

 exposed in either of the other sections. 



D,.,„ correspond to part of Ag^, C,_9 come about twenty-five feet 

 above A.,y, and D,,..,,, come directly above C,..j, thus making a tolerably 

 complete exposure of all the beds of the Chazy. The following table 

 shows the relation of our sections to that of Brainerd and Seely : 



Brainerd Raymond, 



and Seely. 



Aj ^ Ai-n 



A., = A,,-u 



A3 — A1+-15 



A^ = Air,-i9 



Bj = A 19-20 



B, = A2n-2-. 



B^ = Ao,.,« 



B^ = A29 



B. = A30, D)-in 

 Ci = A:„-35 



C, = A36-39, Cx.9, Dis_.in 

 C-; -= Cn • 



The accompanying diagram illustrates the relation of sections A, C, 

 and I) to each other, and the relation of all to the section made by 

 Brainerd and Seely. 



Suhdii'isions According to Faiinules. — ■ The study of the range of 

 species in the \"alcour Island section shows that on paleontologic 

 grounds the strata may be divided into three divisions, each distin- 

 guished by certain characteristic species. Within certain of these 



