312 Canadian Record of Sctence. 
In that region there are two phases of the Olenellus fauna 
found at different levels in the measures of the Cambrian 
System, which may be distinguished as the Olenellus- 
Dorypyge phase, and the Olenellus-Bathyuriscus (cf. Ogygia) 
phase: it is the former only which is known in Hastern 
North America. 
According to Mr. Walcott’s sections, of which an outline 
is given on Table II, page 311, these two phases are separ- 
ated by about 1,200 feet of measures, and the older is found 
some 1,500 feet or more above the base of the Cambrian 
system. 
I have attempted to trace, by dotted lines, the respective 
horizons marked by these two phases of the Olenellus 
fauna, and for comparison, the position also of the Upper 
Cambrian fauna in the same region. 
The basal measures of the Cambrian System, which in 
these sections are indicated by the letter A, are found in 
Norway, Russia, Newfoundland, New Brunswick and West- 
ern America, and probably also in Wales. As for the Cam- 
brian measures which are above these, when they can be 
indicated with sufficient certainty, the Lower Cambrian is 
marked by 1, the Middle Cambrian by 2, and the Upper 
Cambrian, by 3, to show the range of the faunas in the 
several sections. 
Mr. Walcott takes the Nevada section as the typical one 
for the West. In this the Upper Olenellus fauna extends 
3,050 feet above the lower ; and beyond this, for 1,600 feet, 
its forms are mingled with those of the Upper Cambrian or 
Potsdam fauna,’ which, from its position, may be con- 
sidered equivalent to the Ceratopye beds of Sweden. If there 
is this mingling of the species of the Olenellus beds with 
those of the Upper Cambrian, no place remains in Western 
America for the great North Atlantic faunas of the Para- 
doxides beds, and of the Lower and Upper Olenus beds. 
The only inference we can draw from this is, that the 
Upper Olenellus fauna and the Passage beds above were 
cotemporary with the three North Atlantic faunas above 
named. 
1 See Bull. U.S. Geol. Survey, No. 30, p. 32. 
