74 



Descriptions of New Species of Fossils 



in the line of the ridges. The intermediate furrows are marked by 

 one or two longitudinal striae. 



This species is larger and the surface-markings coarser than C. 

 JV^iagarensis. In general aspect and surface-marking it may be 

 compared with C. Tonga and C. lata, but the cone has apparently 

 been wider than the first of these and not so expanded as the last. 

 No entire individual has been seen. 



COLEOLUS' SPmULUS 71. Sp. 



Form a very slender, elongate cone, slightly curving near the 

 apex. Section circular. Length from 2 to 8 mm. Surface orna- 

 mented by fine, sharp, annulating, regular striae, 15 to 20 in the space 

 of 1 mm. 



This is the only species yet described from Silurian rocks. Speci- 

 mens are found in considerable numbers in the softer portions of the 

 shale associated with Leperditia, Beykichia, and other minute forms 

 which are obliterated in the coarser or pyritiferous shales. 



CEPHALOPODA. 



Oethoceras medullare. 



This species, described in the 20th Report on the State Museum 

 of Natural History, is of frequent occurrence in the Magnesian 

 Niagara limestone of Wisconsin; several specimens have been ob- 

 served in the Waldron collections. It usually occurs in an imper- 

 fect and much macerated condition ; only one specimen has been 

 observed which preserves distinctive characters. 



Orthoceras amycus n. sp. 



Shell very gradually and almost imperceptibly enlarging from 

 the apex ; section circular ; septa deeply concave, distant from 

 each other nearly two-thirds the diameter of the tube ; siphuncle 

 central or slightly excentric, diameter at the septum one-sixth the 

 diameter of the tube ; marked by low rounded annulations which 

 are slightly oblique to the axis of the shell, two to three annula- 

 tions in the space of one chamber ; 24 annulations in the space of 

 100 mm. 



^ Coleolus Hall, unpublished nov. gen., Pal. N. Y., vol. v. part ii, page 184. 



