CHAPTER VIII. 
BHAUNAS OF SILURIAN AGE. 
The geologic formations in New Jersey which are here referred 
to the Silurian are the Shawangunk-Green Pond conglomerate, the 
Medina-Longwood sandstone, the Poxino Island shale, the Bossard- 
ville limestone, the Decker Ferry formation, the Rondout formation 
and the Manlius limestone. Of all these the Shawangunk-Green Pond 
conglomerate, the Medina-Longwood sandstone, the Poxino Island and 
the Bossardville formations have not been found to be fossilferous, 
their strata being absolutely destitute of organic remains so far as 
investigations have been carried. The Decker Ferry formation, on 
the other hand, is highly fossilferous and contains a most interest- 
ing fauna of Silurian age. The fauna is not entirely homogeneous 
throughout, as several distinct life zones have been recognized, as 
already described in an earlier portion of this report. The fauna, 
however, has much in common throughout, and all the species, in 
whichever zone they may occur, are here described in one faunal 
group. 
The fauna of the Rondout formation is very different from the 
Decker Ferry fauna, being constituted almost exclusively of Ostra- 
code crustaceans belonging to the genus Leperditia, while in the 
Manlius limestone there is a recurrence of the brachiopods and other 
forms of life which were present before the Rondout time, associated 
with numerous ostracode crustaceans. 
(217) 
