T. N. Dale—Clay-slates and Grits of Poughkeepsie. 59 
with thin strata of limestone. The grit is sometimes slightly 
calcareous. 
The geological significance of these fossils is evident. I 
quote, however, from Hall :* ‘“ Orthis testwlinaria : This species 
rarely, or never, appears in the Utica slate, but reappears near 
the middle of the Hudson River shales, and continues nearly 
to their termination, being abundant at Turin, Lorraine, Pu- 
laski, and other places. It is more rarely found in the vicinity 
of the Hudson River and in the Mohawk valley.” p. 288. “Or- 
this pectinella: This species, though not usually abundant, occurs 
nevertheless in nearly every part of the Trenton li 
though unknown to me in the Hudson River group.” p. 128. 
** Leplena sericea : The thin layers in the lower part of the Tren- 
ton limestone are often entirely covered with the perfect shells or 
separated valves of this species. -It occurs in all localities of the 
Trenton limestone. It also reappears in the Hudson River 
group, being in some localities very abundant.” p. 110. 
shells of this species.” p. 105. The occurrence of these fossils in 
these localities would then establish the fact that the clay-slates 
and shales in the vicinity of Poughkeepsie, on both sides of the 
river, are fossiliferous and that they very probably belong 
to the Hudson River group, as indicated by Mather in 1 48, 
certainly to some member of the Trenton Period. These facts 
also speak in favor of the retention of the term Hudson River 
group as advocated by Hall.t 
Poughkeepsie, N. Y., Dec. 12, 1878. 
Supplementary Note-—A visit to Marlborough on the west 
bank of the Hudson River, about eight miles south of Pough- 
keepsie, has just yielded the following results. In an outcrop 
of argillaceous schist near the river: Orthis testudinaria, Orthis 
 pectinella, Leptena sericea and Crinoid stems In a slightly cal- 
- careous grit at the southern extremity of Marlborough Moun- 
a 5D A 
tain, there called Break-neck Hill, about three miles west of 
the river at this point: Orthis testudinaria. 
Poughkeepsie, N. Y., Dec. 16, 1878. 
* Nat. Hist. of N. Y. Paleontology, vol. i. : 3 
+ See Note upon the History and Value of the term Hudson River ag fog 
American Geological Nomenclature, by James Hatz, of Albany, N. Na ne me 
ings of the Amer. Assoc. Adv. Sci., 187%. This Journal, vol. xvi, p. 482- 
