46 



rugenious sandstone, which contains a multitude of 

 other fossil remains, particularly a large species of 

 Productus and of Terebratula. It is said to have 

 been found in Ulster county, in the State of New 

 York, by the late Charles Wilson Peale, Esq., the 

 distinguished founder of the Philadelphia Museum. 

 During the memorable search after the bones of the 

 Mastodon Giganteum, in the marl pits of that county, 

 this enterprising naturalist procured our Asaph with 

 many other remarkable petrifactions. The rocks 

 which contain them were probably found not in situ^ 

 but were masses rolled from the neighbouring Shaw- 

 angunk mountains,* which by some geologists are 

 supposed to be a link in the grand chain of the Alle- 

 ghanies. Mr. R. Peale, of New York, lately visited the 

 rich repository of fossils in Ulster County, and pro- 

 cured a number of specimens of the A. Laticostatus, 

 all of which he has kindly permitted me to examine. 

 These are much smaller than our cast, but in many 

 instances the caudal elongation is perfectly de- 

 veloped. The A. Laticostatus also occurs in the 

 Helderberg mountains, specimens of which are in the 

 Albany Institute. 



ASAPHUS SELENURUS.! Eaton. Casts Nos. 14 & 15. 



Cauda semilunarij costis angustis, valde distinctis; 

 abdominis articulis duodecim; corpore convexo. 



* The Lenape tribe of Indians, who formerly inhabited this 

 district of country, gave the name of Shawangunk to this stu- 

 pendous ridge of hills a name which has been very properly pre- 

 served. 



t Derived from Selene, moon, and ouros, tail. 



