GRAPTOLITES OF NEW YORK, PART 2 5 c 



but not before observed in North America.' Its finding in the northeastern 

 corner of this continent is therefore of some interest. It is in Europe a 

 form of the lowest Siluric, occurring there in the lower Rastrites shales. 

 Tullberg [1882, p. 76 ff| records it from the last zone of the Champlainic 

 (Ordovicic) (zone of Diplograptus sp. and Climacograptus scalaris) and the 

 first two of the Siluric (zones of Monograptus gryphus and M. gregarius), but 

 Lapworth considers the first named zone as already constituting a basal 

 zone of the Siluric. Tornquist records it from the first, third and fourth 

 zones of the Scanian Rastrites beds. 2 While its occurrence in Maine with- 

 out other associated species will thus not suffice to fix the exact horizon of 

 the bed, it serves to demonstrate the presence there of the Rastrites beds 

 of Europe and the development of the Siluric in a facies not known 

 elsewhere in North America. 



2 Rochester sJiale and Lockport limestone 



The later Niagaran has in the United States afforded graptolites in 

 only two localities, namely : in the Rochester shale of New York and the 

 Bainbridge limestone of Missouri. In Canada a very rich dendroid fauna 

 has been obtained in the Niagaran limestone of Hamilton, Ontario, and a 

 Dictyonema in the Niagaran of the eastern provinces. The following is a 

 list of the forms of the United States, here described : 



1 Dictyonema retiforme Hall 8 Inocaulis plumulosus Hall 



2 D. gracile Hall 9 I. divaricatus Hall 



3 D. polymorphum Gurley ms. 10 Acanthograptus walkeri Spencer 



4 D. subretiforme (Spencer) 11 Palaeodictyota anastomotica (Ringue- 



5 D. areyi Gurley ms. berg) 



6 Desmograptus pergracilis (Hall 6° Whit- 12 P. bella (Hall) 



field) 13 Chaunograptus novellus Hall 



7 Cyclograptus rotadentatus Spencer 14 Cyrtograptus ulrichi nov. 



'The forms described by Hall as Graptolithus scalaris are scalariform 

 aspects of Champlainic graptolites. 



2 See more detailed statement of range and distribution of this form in the species 

 description. 



