68 AMADEUS W. GRABAU 



in New York. The fauna is rapidly changing, the true Upper Ordo- 

 vicic faunas begin to appear, and soon the typical Utica fauna, with 

 Glossogmptus quadrimucronatus, Climacograptiis typicalis, Cory- 

 noides curtus, and, less frequently, Leptograpius Jlaccidus, Dlcrano- 

 graptus nicholsoni, and Climacograptus putillus is established. The 

 association of typical Utica graptolites with characteristic Trenton 

 limestone fossils, as Trocholites ammonius, Cameroceras proteijorme, 

 and Schizocrania fdosa, bears on the previously discussed question 

 of the synchroneity of the Utica and Trenton. 



Climacograptus typicalis, the typical Utica species, is reported 

 by Winchell and Ulrich from the Fusispira and Nematopora Iseds 

 of the middle Galena of Minnesota. Since the Galena of that section 

 follows directly upon the Black River, this occurrence is only a short 

 distance above the base of the Trenton, which is thus indicated to 

 be the western limestone equivalent of the Utica shale of the east. 

 As already noted Ruedemann has cited abundant evidence of the 

 gradual westward extension of the successively higher zones of the 

 Utica, and the replacement of the limestone phase (Trenton) by them. 

 The Galena-Trenton limestone of the Lake Winnepeg region con- 

 tains Dictyonema canadense (Whiteaves), Thamnogrnptus afjinis 

 (Whiteaves), and the typical Utica species, Climacograptus typicalis 

 (Hall). Whiteaves concludes that the Galena-Trenton of Lake 

 Winnepeg "most probably represents the whole of the Utica and 

 Trenton formations, inclusive of the Galena.'" 



THE CINCINNATI GROUP 



This is the upper calcareous phase of the latest Upper Ordovicic, 

 and comprises, in ascending order, the Eden, Maysville, and Rich- 

 mond. The Eden was formerly correlated with the Utica, but the 

 underlying Trenton mainly represents that formation. The Eden 

 is in part equivalent to the Frankfort shales, though the occurrence 

 of Climacograptus typicalis in the Eden strata would favor its former 

 correlation with the Utica. The Maysville represents later Lorraine 

 as developed in New York, though the fauna, being that of a cal- 

 careous facies, is markedly different. 



Ulrich has reported a disconformitv at the base of the Eden, 

 in the Cincinnati section, but this, if it exists, does not appear to be 



I Quoted by Ruedemann, op. cit., II, 28. 



