Clinton and Niagara Strata. — Sarlc. 299 
reaches its most striking development among these reef forms. 
This he speaks of as "Colonial Tendencies." f 
Dr. Robert Bell 4! has described great cavernous masses of 
limestone occurring in thin bedded, nearly barren limestone of 
Devonian age, on the Attawapishkat river, Canada. They are 
made up of a few species of fossils including corals. These 
from their form and contents suggest our reefs of the Clinton 
and Niagara. 
Dr. G. K. Gilbert and F. P. Gulliver§ describe the cores of 
the Tepee Buttes of Colorado, as hard squamous masses of 
limestone of elongate cylindrical form, resting in the soft shales 
of the Fort Pierre Cretaceous. The authors are inclined to re- 
gard them as formed by colonies of Lucina occidentalis-ventri- 
cosa, of whose remains they are mainly composed. From their 
having so many features in common with the masses described 
by Dr. Bell, they regard their close relationship unquestionable. 
A SCHEMATIC STANDARD FOR THE AMERICANT 
CARBONIFEROUS. 
By Charles R. Keyes, Des Moines, Iowa. 
In the attempts to parallel, in America, the various sub- 
divisions of the Carboniferous, there has always been more or 
less difficulty in securing results that are even approximatelv 
satisfactory. The sections of the East, of the Interior, and 
of the West, appear at first glance to have no c<omparable ele- 
ments. In consequence, the eastern, or Pennsylvania, suc- 
cession, having been the first to be carefully studied, has come 
to be regarded as the section to which all others oif the con- 
tinent must be eventually referred. As for the rest of the 
continent, little consideration is given it so far as concerns 
any serious effort to establish general sections with which all 
others in each prcivince might be compared, and whioh in its 
serial subdivisions, at least, could be arranged with reference 
to a schematic section. 
One main reason for this rather anomalous state of the 
subject is, of course, the fact that the boundaries between 
\Ibid, pp. 184-196, 
XGeol. and Nat. His 
5, 28G. 
^Bull. Geol. Soc. Am., vol. vi, pp. 333-342, part 17. 
XGeol. and Nat. Hist. Survey of Canada, Ann. Kept , vol. ii. (1S86). pp. 
27G, 28G. , V -/. HH- 
