176 F. B. Meek and A, H. Worthen on the Age, etc. 
feet in thickness, the questions naturally suggest themselves,— 
are we right in referring these Chouteau beds to the horizon of 
the Chemung? Can it be possible that a great formation like 
the Old Red Sandstone, characterized by the remains of a pecu- 
liar fauna of its own, is wanting here between the Chouteau and 
Burlington limestones ? 
ut on the contrary, it may be said, if we do not adopt this 
conclusion, what are we to do with the fossils occurring in these 
rocks apparently identical with Chemung species? In reply to 
this latter question, we would state that although we have for 
a long time thought a few species occurring in the Chouteau beds 
identical with Chemung forms, later comparisons with New York 
specimens from the latter formation, lead us to doubt their actual 
specific identity. They are generally obscure casts of Avicu 
and other lamellibranchiate mollusca, some of which also resem- 
does 
here in the same beds with numerous other fossils totally dis- . 
us in placing these beds on a ieee with the Chemung group* 
M ite, in discussing this question in his paper already 
equivalency, but does not necessarily prove that they were con- 
temporaneous. Indeed, it seems sro 
Old Red of the Katskill Mountains?” : 
If any of the species found in the strata under consideration 
are really identical with Chemung forms, as has been sup ’ 
Mr. White’s suggestion that they had prolonged their existence 
by migrating westward, until long after the close of the Chemung 
epoch in New York, is not improbable, but in that case, we 
should not refer the rock in which they occur to the Chemung, 
but either to the Old Red, or to the Carboniferous, for in using 
any of these names we refer to a period in time, as well as to a 
group of strata. The entire group of fossils, however, found in 
hese beds is far more nearly allied to the Carboniferous fauna 
than to that characterizing the Old Red either in this country oF 
