GRAPTOLITES OF NEW YORK, PARI' 2 4^ 



1/ 



evidence that this species does not range beyond the Utica formation. In 



Canada it has been identified with some doubt by Ami in collections from 

 the Utica shale of Lacolle, Quebec, ami from the north shore of Lake Huron 

 and the Manitoulin islands. 



The last mentioned citation is the only record of the possible presence 

 of C . b i c o r n i s in the Mississippian sea in Posttrenton time. But it was 

 well established there in early Trenton (Normanskill) time, as evinced by 

 its frequent occurrence in the graptolite beds of Arkansas [Gurley, 1890]. 

 At that time it probably occupied the entire Pacific basin, for it has been 

 recorded by T. S. Hall from the same horizon and many localities in Vic- 

 toria, Australia. It is equally well known from the corresponding beds of 

 the Atlantic basin in Great Britain where Nicholson and Lapworth have 

 found it in man)- places. Lapworth [ 1878, p. 250; 1880, p. 283, 358] cites it 

 as one of the Glenkiln or Llandeilo-Bala and Bala-Caradoc forms, marking 

 it as passing through the entire series of Hartfell zones. Its British range 

 would hence correspond to ours with the exception that it seems to exist 

 there to the end of the Champlainic. It is likewise known from Scandinavia 

 (Tullberg). 



Remarks. This species, which has been made the genotype of Clima- 

 cograptus by Hall, is not only the most stately and most common of our 

 representives of the genus, but also the most conspicuous by reason of the 

 remarkable appendages of its sicular extremity. These show such a wide 

 range of modifications that several of them have been recognized as varieties 

 (p e 1 t i f e r , tridentatus and 1 o n g i s p i n u s) . On account of their 

 bearing on the morphology of the graptolite spines in general we have dis- 

 cussed them separately in the introductory chapter on spines [see p. 80], 

 stating there that all these varieties occur in the Normanskill shale together 

 with transitional forms, indicating the climacteric condition of the species 

 at the time. 



