320 The America?t G.eologist. November, 1900 
one-fourth of the brachiopods that might be considered as 
forming a new faunal clement. 
The importance of the introduction of a newer, or geologi- 
cally younger faunal element is fully recognized, but it is not 
believed that its appearance should entirely overbalance the 
existence of greatly predominating older elements. We' can 
hardly consider a new faunal age to begin with every initial 
introduction of a new faunal element. Faunas have their 
beginnings far down in the depths of older faunas. They ex- 
pand, displace the older elements and culminate. They decline 
and fade away far up among still newer faunas. We have anal- 
ogous examples in the progress of nations. The initiation of a 
new element does not indicate a new dynasty. A new political 
movement has its birth midst a multitude of conflicting ele- 
ments. It may grow in importance and finally displace the 
existing government. Only when it has overcome the older 
ruling powers is a new regime inaugurated. Not until then 
does the nation require a new name. There are long steps be- 
tween the initiation of a new element and the initiation of a 
new regime. 
If a new regime^ a Carboniferous regime, is initiated at the 
basal horizon of the Louisiana limestone the actual evidence 
afforded by the 81 species enumerated from the Chonopectus 
sandstone, which is regarded as pre-Louisianan in age,* ap- 
pears to be far from demonstrating it. The consideration of 
the other and related faunas may give more substantial proofs. 
However, on this point it is probably best to suspend judg- 
ment until the "Faunal Kinderhook Studies" viow^ in progress 
are completed, since for the first time evidence along these 
lines promises to be exhaustive. 
The still later statement in which Weller* regards all of the 
Burlington section below the Productal limestone, (Bed No. 4) 
as older than the Louisiana limestone, suggests another in- 
teresting consideration. The inference is that this writer con- 
siders the most marked faunal change to take place at the base 
of the Productal limestone. If the view I have already ex- 
pressed be the correct one, that this horizon at Burlington is 
to be considerd as equivalent to the base of the Chouteau lime- 
stone farther south at Louisiana, as the stratigraphy seems 
*Iowa Geol. Siir., Vol. X, p. 79, 1900. 
fLoc. cit. 
