PHVSICAL AND FAUNAL. EVOLUTION 233 
in New York. The fauna is rapidly changing, the true Upper Ordo- 
vicic faunas are appearing, and soon the typical Utica fauna, with 
Glossograptus quadrimucronatus, Climacograptus typicalis, Cory- 
noides curtus, and, less frequently, Leptograptus flaccidus, Dicrano- 
graptus nicholsoni, and Climacograptus putillus is established. The 
association of typical Utica graptolites with characteristic Trenton 
limestone fossils, as Tvrocholites ammonius, Cameroceras proteijorme, 
and Schizocrania filosa, 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 beds 
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), Thamnograptus affinis 
(Whiteaves), and the typical Utica species, Climacogra ptus ty picalis 
(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 Climacogra ptus 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 disconformity at the base of the Eden, 
in the Cincinnati section, but this, if it exists, does not appear to be 
t Quoted by Ruedemann, of. cit., I, 28. 
