76 PALEOZOIC PALEONTOLOGY 
jantic in the neighborhood of Chesapeake bay. Although deposited in’ 
an entirely distinct basin, the Decker Ferry formation, as well as the 
subjacent beds down to the Medina formation, were probably con- 
temporaneous with some portion or the whole of the Niagaran for- 
mations of the interior. 
The incursion of faunas from the exterior into the Cumberland 
basin culminated with the Helderbergian faunas, and for that reason 
Ulrich and Schuchert* have spoken of that chapter in the faunal 
history of North America, covering the history of the life of the 
Cumberland basin, as the Helderbergian invasion. The earliest faunal 
evidence of this invasion in New Jersey is to be found in the Decker 
Ferry formation,but further south, according to Ulrich and Schuchert, 
there are faunas belonging to this invasion older than the Decker 
Ferry of New Jersey. 
The Decker Ferry fauna is allied to the Silurian faunas of the 
Atlantic province, which extends along the Atlantic border in New 
England and Eastern Canada, but sufficiently detailed study of these 
eastern Silurian faunas for detailed comparison with other faunas 
has never been made. | 
RONDOUT FORMATION. 
In the Nearpass section the thirty-nine feet of strata lying above 
the Decker Ferry formation are referred to the Rondout formation. 
The beds consist of more or less earthy shales and limestones, which 
are usually sparsely fossiliferous, although in some beds gstracode 
crustaceans belonging to the genus Leperditia are abundant. But a 
single specimen of a brachiopod has been found in these beds in New 
Jersey in connection with the field investigations for the preparation 
of this report. | 
Locality 2A.—At the Nearpass quarry the following section of 
these beds, with the fossils identified from them, has been recognized : 
2 Al4. Earthy shale, with limestone bands. 3 ft.j2 sine 
1. Leperditia sp. undet. 
2 A, Fine-grained, dark limestone. 6 ft. 4 in. 
1. Leperditia elongata n. sp. 
2 A'®. Thin-bedded, calcareous shale, with no fossils. 1 ft. 651m 
2 A, Hard, fine-grained, blue or gray, brittle lime- 
stone. 2 Tt wees 
1. Hyatella lamellosa n. sp.’ 
2. Leperditia gigantea n. sp. 
* Loe. cit., p. 648. 
