FORMATIONS OF SILURIAN AGE. VS 
and it is believed that the beds containing the upper faunal zone of 
the formation, characterized by Atrypa? lamellata, may be definitely 
correlated with the Coralline limestone of New York, and that the 
entire Decker Ferry formation is the southern extension of that 
formation. 'The coralline age of these beds was first recognized by 
Dr. 8. T. Barrett,* a local geologist of Port Jervis, and to him credit 
is due for the first announcement of the presence of strata in the 
New Jersey section referable to the Coralline limestone of Eastern 
New York. ' 
Among the species which are unknown except in the Decker Ferry 
fauna we find forms more or less closely allied to Western Niagaran 
and to Helderbergian species, but there seem to be sufficient differ- 
ences in all cases to constitute distinct species. Among the orthids, 
both Dalmanella postelegantula and Rhipidomella preoblata are in- 
termediate in their characters between Niagaran and Helderbergian 
species. Rhynchonella deckerensis and Rhynchonella agglomerata are 
both probably ancestral to Helderbergian species. Wilsonia globosa 
_is of a Silurian type, the similar rhynchonelloids of the Helderbergian 
faunas being members of the genus Uncinulus. The small variety of 
Spirifer vanuxemi, called var. minor, is closely allied to the typical 
form of the species, which is one of the most characteristic Manlius 
limestone species. 
In his original description of the fauna of the Coralline limestone, 
Hallt considered these beds in Eastern New York to be the eastward 
extension of the Niagaran strata in the western portion of the State. 
The great dissimilarity between the Coralline or Decker Ferry fauna, 
however, and that of the Niagaran formations further west indicates 
that the strata containing the two faunas were deposited in two dis- 
tinct basins of sedimentation, which were either entirely separated 
from each other by a land barrier or their connection was very slight 
or indirect. The great interior epicontinental sea of Niagaran time 
is believed to have had its connection. with the oceanic waters by a 
northern passage through the Hudson bay.{ The Decker Ferry fauna 
lived in a sea which has been called the Cumberland basin by Ulrich 
and Schuchert,§ which occupied a rather long and narrow area in 
the Appalachian region and had its oceanic connection with the At- 
* Ann. N. Y. Acad. Sci., vol. 1, pp. 121-124 (1878); Am. Jour. Sci. (3), vol. XV., 
pp. 370-372 (1878). 
7 Pal N. Y., vol. IL, p. 321. 
{Jour Geol., vol. VI., pp. 692-703. 
¢ Rep. N. Y. State Pal. for 1901, p. 649. 
