FOSSILS OF THE NIAGARA GROUP. 391 



GENUS CYCLONEMA, Hall. 



Cyclonema'? elevata, n. s. 



PLATE XV, FIG. 4. 



Shell conical ; spire elevated, gradually tapering, embracing an angle of 

 about forty-five degrees. Volutions rounded, ventricose, about five ; 

 gradually enlarging to the aperture, which has been nearly circular. 



The cast from which the species is described, possesses evidence of 

 revolving strise, without indications of a central band. 



Height nine-tenths of an inch ; width six-tenths of an inch. 



Formation mid Locality. — In limestone of the Niagara group, at Racine, 

 Wisconsin. 



GENUS HOLOPEA, Hall. 

 HOLOPEA haemonia'? Billings. 



Holopea harmonia, Billings. New species of Silurian FossUs, p. 158, fig. 142. 1862. 



There are several specimens in the collection, so nearly corresponding 

 with the figure given by Mr. Billings, that I must regard them as the 

 same species. In a specimen of the same size as the figure cited, 

 the middle of the last volution is subcarinate and flattened above. The 

 spire is a little more elevated than the figure, and the last volution a 

 little more ventricose below. It may prove to be a distinct species. 

 Another specimen of similar form does not possess the flattened band, 

 while the lower side of the last volution is flattened. 



Formation and Locality. — ^In limestone of the Niagara group, at Racine, 

 Wisconsin. 



Holopea guelphensis, Billings. 



plate XV, FIG. IS. 

 Holopea guelphensis, Billings. New species of Silurian Fossils, p. 159, fig. 143. 1862. 



Several fragments of a species, differing from any other in the collec- 

 tion, resemble the Canadian species ; but being all quite imperfect, no 

 full comparisons can be made. 



Formation and Locality. — In limestone of the Niagara group, at Racine, 

 Wisconsin. 



