TRENTON CONGLOMERATE OF RYSEDORPH HILL 35 



trochonema Salter 

 Trochonema umbilicatiim Hall sp. 

 Pleurotomaria u m b i 1 i c a t a Hall. Pal. N. Y. 1847. 



J "1 i O 



A pebble of gray crystalline limestone from the Rysedorph hill 

 conglomerate was found to be filled with specimens which in all 

 essential feature© agree with the descriptions of Trochonema 

 umbilicatum given by Hall, Salter, Ulrich and Scofield, 

 with the slight exception that the space between the suture and 

 the first carina is not as flat as in most specimens, but rather 

 concave. The carinae are more distinct than in any specimen 

 figured by Hall. This form possesses a great vertical range, from 

 the Lowville limestone to the Lorraine beds, and wide geographic 

 distribution, being reported from Baffin Land, Lake Winnipeg, 

 New York and the Trenton of the Mississippi basin. (Group 7) 



holopea Hall 

 Holopea paludiniformis Hall. Pal. N. Y. 1847. 1:171 

 A large internal cast of this rare species, of which Hall reports 

 that he obtained only one specimen (also a cast) from the crys- 

 talline upper part of the Trenton limestone at Watertown, was 

 found in a pebble of compact black limestone at Rysedorph hill. 

 Our specimen differs slightly from the type in having the volu- 

 tions a little less ventricose and in its umbilical perforation. The 

 form is not mentioned by later collectors with the exception of 

 Ulrich and Scofield, who have referred a species from the lower 

 Trenton in Minnesota to this species. This also is said to have 

 a small umbilical perforation. (Group 5) 



[-> cyrtospira Ulrich 



Cyrtospira attemiata sp. nov. 

 PI. 2, fig. 8 



A single specimen of Subulites was found in the gray crystal- 

 line limestone, which by its strong curvature is of a striking 

 appearance to the eye accustomed to the rigidly erect species of 

 the New York forms of Subulites. 



