I20 NEW YORK STATE MUSEUM 



nema flabelliforme ruedemanni, mixed with f 1 a - 

 belliforme acadica, norwegica, desmograp- 

 t o i d e a and Staurograptus. 



We will thus distinguish the following zones : 



b Zone of Staurograptus dichotomus. 

 a Zone of Dictyonema flabelUforme. 



In part I of the Graptolites of New York (N. Y. State Mus. Mem. 

 7, 1904, p. 496), the writer has distinguished a suhhorizon of Clono- 

 grap'tus cf. -flexilis, a few fossils of which were found on the road 

 from Albany to Def reestville. It was predicted there that the species 

 of Clonograptus (flexilis, rigidus) described 

 by Hall from Quebec would be found to represent a separate horizon 

 between the Schaghticoke and Deep Kill horizons. Raymond^^ has 

 since recognized this horizon as forming the base of the Point Levis 

 series. He cites Clonograptus flexilis and C. 

 rigidus, Tetragraptus quadribrachiatus, 



T . s e r r a and T. approximatus as characteristic 

 fossils. The next higher horizon at Point Levis is that with Phyllo- 

 graptus typus, Tetragraptus quadribrachiatus and Didymograptus 

 octobrachiatus. Also this horizon fails to be exposed in our Deep 

 Kill section, but is probably present directly below our first horizon 

 of the Tetragraptus bed, as indicated by the frequent occurrence 

 there of the tetragrapti with the dominant species of Didymograptus. 



Upon this follows our Tetragraptus zone of Bulletin 52. The 

 detailed list of fossils, given in Memoir 7 (1904), page 504, however, 

 brings out the fact that this zone is divisible into two subzones cited 

 as bed i and bed 2. The first is characterized by Didymo- 

 graptus nitidus and D . p a t u 1 u s and will be desig- 

 nated as the suhzone of Didymograptus nitidus and D. patulus. The 

 second (bed 2) is characterized by the abundance of Didymo- 

 graptus extensus. Go n i o gr ap t us thureaui, 

 G. perflexilis and Tetragraptus fruticosus, 

 T. quadribrachiatus and T . s i m i 1 i s . We will 

 distinguish it as the suhzone of Didymograptus extensus and Gonio- 

 graptus thureaui. 



Upon this follows the zone of Didymograptus hiUdus which is 

 likewise divisible into two subzones, the first of which (bed 3) is 

 characterized, besides Didymograptus bifidus, by 

 Goniograptus geometricus, Tetragraptus 



^ Percy E. Raymond, The Succession of Faunas at Levis, P. Q. Amer. 

 Jour. Sci., 38: 523. 1914. 



