DEVONIAN AND MISSISSIPPIAN FAUNAS 269 
beds younger than the Hamilton; the remaining species are common 
to the Onondaga and the Hamilton, with one exception, which occurs 
in the Hamilton and the Chemung. From these figures it is evident 
that this Great Basin fauna contains a strong Onondaga element, 48 
species in all. Of the Hamilton species neither Tropidoleptus cart- 
natus,* Chonetes coronatus, nor any of the strictly foreign species in the 
fauna are recognized, the entire Hamilton element being of that associa- 
tion which seems to have originated from the Onondaga. Of the three 
highly characteristic elements of the Onondaga fauna of the East, 
corals, cephalopods, and fishes, we find 11 species of corals and 11 
species of cephalopods, but none of the latter are identical with those 
of the East, although they are congeneric. Of icthyc remains but a 
single tooth was collected by Walcott, but in the Kanab Cafion of 
northern Arizona a strongly marked Devonian fish horizon is recorded,? 
although the composition of the fauna has not been made known. 
In its entirety the Devonian fauna of the Western Continental 
Province may be said to be composed of a combination of two distinct 
elements: (1) the Middle Devonian fauna of the Eastern Continental 
Province, exclusive of the southern hemisphere element in the Hamil- 
ton, and (2) the fauna of the Interior Continental Province. These 
two elements are not fully differentiated in the faunas, since species 
from the Iowan or Mackenzie Basin faunas occur indiscriminately in 
either the lower, middle or upper divisions of the Great Basin Devo- 
nian. The Onondaga element also occurs through all of the divisions, 
although it is most conspicuous in the lower beds. Within this proy- 
ince there is no faunal evidence indicating the presence of Devonian 
rocks of greater age than the Onondaga, but sediments were doubt- 
less deposited in the area contemporaneously with the Onondaga, 
Hamilton, and Upper Devonian of the Eastern Continental Province, 
but no beds can be correlated definitely with either of the eastern 
formations. The older of the beds are doubtless of greater age 
than the oldest Devonian beds of Iowa, although they may not be 
older than some of those of the Mackenzie Valley. 
1 Tropidoleptus carinatus has been recorded from the Pinon Range, Nevada, 
but the species has not been figured, and the identification has not been confirmed, 
Monograph, U.S. G.S., VIII, 276. 
2 Walcott, Monograph, U.S. G.S., VIII, 7; also Am. Jour. Sci. (3), XX, 225. 
