76 Forty-sixth Beport on the 



arenaceous members of the group as to leave no doubt that the 

 strata belong to the Hudson River age, though it can not be 

 proved at the present time that they lie at the base of the 

 formation. 



The work on the Geological map has been carried on without 

 especial reference to the collection of fossils, since this work had 

 already been done over the larger part of the country examined. 

 In a comparativel}^ few^ cases specimens were collected as records 

 of the outcrop and locality, in order that the age of the formation 

 might be determined by the contained fossils. 



In the course of the investigations for the Geological map a 

 considerable number of interesting specimens have been obtained, 

 which have been collected for the determination of the age of 

 the outcrops, and the limits of certain formations, especially of 

 the Hamilton, Portage and Chemung groups, and are of interest 

 to the Museum collections. These specimens have been placed in 

 drawers for future study and verification of the age of the expos- 

 ures as laid down on the map, by their fossil contents. The 

 following li^s may be usefully recorded in their geological order : 



A specimen of partially altered Hudson River shale from West 

 Park, from strata almost vertical, and containing Orthis testii- 

 dinaria, giving evidence of the age of the formation. The Hudson 

 River shales with Graptolites, outcrop at a point one mile farther 

 south along the line of the railroad, and we have good specimens 

 in the collections made some years ago. 



Fossiliferous Shaly lime-stone lying above the Scutella or 

 Becraft limestone near Hudson. This upper shaly limestone was 

 first noticed, and attention called to its occurrence in the 

 neighborhood of Rondout, by Prof. William M. Davis, of Cam- 

 bridge, Mass., and has now been full}'- recognized at Becraft' s 

 Mountain. Twenty-four specimens. 



Specimens of Shaly limestone from a small synclinal outlier 

 near Cornwall. At this place the Pentamerus and associated 

 limestones which form the great escarpment of the Helderberg 

 have become very greatly attenuated, and are standing almost 

 vertically as seen in the railroad cutting near Cornwall. The 

 shaly limestone specimens are from a locality three-fourths of a 

 mile southwest from Cornwall station, and contain the charac- 

 teristic fossils of that rock. Specimens labeled with localit}'. 



