2 2 NEW YORK STATE MUSEUM 



had found [Mem. 7, p. 503] in the Deepkill graptolite faunas an element 

 which strongly urged a closer connection of the same with the homotaxial 

 Australian faunas, and for this reason inferred an open marine connection 

 of the Levis channel southward or westward with the Pacific ocean ■ — 

 besides occasional openings of the basin to the Atlantic by means of the 

 Newfoundland embayment — a view which has meanwhile received further 

 support by the recognition of the presence of Mississippian (and Pacific) 

 elements in the cephalopod faunas of the equivalent limestone beds in the 

 adjoining Chazy basin. 



Since now the Upper Cambric Dictyonema shale, the rocks of the 

 Deepkill horizons corresponding to the Beekmantown and those of the third 

 zone, probably homotaxial with the Chazy, as well as the Dicellograptus 

 zone, and, as shown further on also the succeeding zone, are coextensive 

 in the Levis basin, the legitimate inference is that graptolitiferous beds 

 were formed in that basin continuously from the Upper Cambric to late 

 Trenton age with the exception of slight transgressions of the Missis- 

 sippian sea in Trenton time, or in other words, that this basin, — or like 

 physical conditions — existed continuously through all these ages, its waters 

 remaining always in connection with the Newfoundland embayment and 

 gaining occasionally access to the Mississippian sea and thereby to the 

 Pacific ocean. I believe that when all graptolite horizons of the Lexis 

 basin with their subhorizons shall have been distinguished and their proper 

 succession recognized, a practically uninterrupted series of graptolite beds 

 will become known extending from the Upper Cambric to the Utica 

 invasion. 



An undubitable Dicellograptus fauna has been made known by Gurley 

 from the novaculite region in Arkansas [ [892, where it was referred to the 

 next zone, and 1896] which also has furnished a Beekmantown graptolite 

 fauna. Although the material is not favorably preserved, the following 

 forms of our Normanskill beds can be clearly recognized : 



Thamnograptus capillaris (Emmons) Didymograptus sorratulus Hall 



Didymograptus sagitticaulis Gurley Ncrm^raptu^ gracilis (Hall) 



