124 NEW YORK STATE MUSEUM 



more distinctly easterly, Atlantic aspect. Here belong the shale on 

 Van Schaick island with Cryptograptus tricornis 

 insectiformis and the shale at Mechanicville (see Mem. 

 II, p. 32) with Climacograptus caudatus and 

 Corynoides curtus comma. There is no doubt iii 

 our mind that these occurrences represent a zone that is older than 

 any of the Canajoharie shale zones and that is equivalent or directly 

 follows upon the shale exposed at Magog, for Climaco- 

 graptus caudatus is found in Sweden only in the lowest 

 of the three subzones of Dicranograptus clingani ^^ and it is also in 

 Great Britain -^ restricted to the zone of Dicranograptus clingani. 

 We have further to see in Cryptograptus tricornis 

 insectiformis, as well as in a number of the Magog species 

 reminders of the nearness of the Normanskill fauna. This earlier 

 zone of the Snake Hill beds may be distinguished as the zone of 

 Climacograptus caudatus. 



A higher horizon is exposed in black shales outcropping on both 

 the east and west shores of Saratoga lake (see Bulletin 169, p. 97, 

 1914) north of Snake Hill. This shale has furnished an abundance 

 of Dicranograptus nicholsoni, besides D i p 1 o - 

 graptus amplexicaulis, with varieties, Climaco- 

 graptus spiniferus. mutations of G 1 o s s o - 

 graptus quadrimucronatus, etc. This horizon of 

 middle or late Trenton age may possibly correspond to the last one of 

 the Canajoharie shale. The abundance of Dicranograptus 

 nicholsoni which is a long range species is noteworthy in 

 view of the fact that we shall meet another outburst of this European 

 species in the middle Utica in an entirely different association of 

 forms. We consider the combination, in a subzone, of Dicrano- 

 graptus nicholsoni, Diplograptus amplexi- 

 caulis and Climacograptus spiniferus as of 

 great interest, but of local importance only. 



Utica Shale 

 Directly upon the Canajoharie shale in the middle Mohawk 

 valley follows the Utica sliale. This has been divided, in a mono- 

 graph of the Cincinnatian of New York, now ready for the press^^ 

 into three zones, namely, 



^S. A. Tullberg; Skanes graptoliter I. Allman ofversikt ofver de 

 siluriska bildningarna i Skane. Sver. Geol. Unders. Ser. C. no. 50, 1882 



^^ Charles Lapworth, Gertrude L. Elles and Ethel M. R. Wood, A Mono- 

 graph of British Graptolites, pt 5, Pal. Soc. 1906, p. 203. 



^ See also paper read before Pal. Soc. America, 1916. Abstract in : Geol. 

 Soc. Amer. Bui., 28 : 206. 



