528 The American Naturalist. [June, 
the principles of petrographic classification, of which the elaboration 
has been confided by the Congress of Ziirich to a special commission 
under the presidency of M. A. Michel-Levy. 
The Committee on Organization of the Congress of St. Petersburg 
does not flatter itself that the single session from August 17th (22d) 
to August 23d (September 5th) will suffice to exhaust this programme, 
but if it be only a part which can be submitted to discussion from 
all points of view—a discussion which would offer to the Congress the 
possibility of expressing itself in a definite sense, the 7th Session of the 
International Geological Congress would still have the merit of having 
directed the labors of the meeting in the right road, abandoned since 
the session at Washington.—P. F. 
On the Laramie and Related Formations in Wyoming. 
—Various questions that have arisen in regard to the contents of the 
Laramie formations have been investigated by T. W. Stanton and F. 
W. Knowlton. They show that the Black Buttes (Wyoming) beds 
are true Laramie, and correlate with them the Ceratops beds of Con- 
verse County. The plant forms confirm the Laramie age of the Cera- 
tops beds. It is also demonstrated that the coal-bearing series of the 
Laramie plains in large part if not wholly, are older than the true 
Laramie. The facts stated by the writers lead them to follow the ex- 
ample of King, Hayden and many other geologists in placing the base 
of the Laramie immediately above the highest marine Cretaceous beds 
of the Rocky Mountain region. They include in the Montana forma- 
tion or division intercalated non-marine beds that at some localities 
yield land plants and brackish and freshwater mollusks as well as 
coal. 
The discussion of the upper limit of the Laramie is replete with in- 
terest and is here given in full :— 
“ Until a few years ago it was the custom to include in the Laramie 
all of the beds between the Fox Hills and Wasatch formations. In 
the Denver region the detailed studies of Cross and Eldridge,’ have 
resulted in the recognition of the Arapahoe and Denver beds separated 
from the Laramie and from each other by unconformities and distin- 
guished by marked lithologic features. A revision of the fossil floras 
of that region has also shown that the Denver beds contain a flora 
composed of species, a large proportion of which are not found in the 
' Proceeds. Colo. Sci. Soc., Vol. III, pt. I, pp. 86-133; Amer. Jour. Sci., 3d 
Ser., Vol. XX XVII, 1889, pp. 261--282; Monograph, XX VII, U. S. Geol. Sur- 
vey (in press). 
