FOSSILS OF THE LOWER SILURIAN. 



85 



PTEROPODA. 

 Genus COLEOPRION Sandberger. 



Coleoprion minuta, n. sp. 

 Plate xi, figs. 17, 17 a; pi. xii, fig. 21. 



Minute, slender, elongate subcylindrical tubes; slightly curved, with a 

 distinct angularity on the outer side, section subelliptical. Average length, 

 8 mm to 10 mm ; average diameter, 1.25 mm at smaller end to 2.25 mm at larger end. 



Surface marked by fine annulations, with very fine concentric striae 

 between, the latter perceptible only under favorable conditions. The annu- 

 lations are narrow, rather sharp, and cross the inner side of the curvature of 

 the tube transversely, bending obliquely backward on each side, and meet- 

 ing at an angle on the slight ridge on the outer side. 



This interesting little species is probably a true Coleoprion, although 

 presenting some differences from the typical species ; .these, however, appear 

 to be rather of specific than generic value. 



M. Barrande describes one species from the Upper Silurian (J&tage E], 

 and one from the Devonian, at which horizon all other species referred to 

 the genus have been obtained. Its range is now extended down to the 

 horizon of the Chazy limestone of the New York series, or the summit of 

 the Pogonip Group of Nevada. 



Formation and locality. Upper Pogonip limestone of Lone Mountain, 

 18 miles northwest of Eureka, Nevada, and at the same horizon on Pogo- 

 nip Ridge, White Pine District, Nevada. 



Genus HYOLITHES Eichwald. 



Hyolithes Vanuxemi, n. sp. 



Plate xi, figs. 16, 16 a, 6. 



Form, a slender, elongate, subtriangular tube, with the lateral margins 

 rounded, gradually tapering from the base to an acute extremity. Trans- 

 verse section semi-elliptical, almost flat on the ventral side, the lateral edges 

 rounded or subtriangular. Ventral face nearly flat transversely and in- 



