The Fauna of the Maxville Limestone. 



415 



become gradually obsolete towards the aperture, where they 

 are not more widely separated than near the smaller end. Traces 

 of fine transverse striae are also seen on well preserved speci- 

 mens ; both between and upon the costae. (Septa and siphuncle 

 unknown). The largest specimen we have seen is about five 

 inches in length (both extremities being incomplete) and 1.83 

 inches in its greatest diameter at the larger end, while its 

 greater diameter at the smaller end is near 0.70 inch." 



" Prof. Swallow has described, from the same 



horizon as this, a similar species under the name 0. chester- 



FiG. 35. — Orthoceras randolphense. A view of an imperfect specimen. 



ensis (Trans. St. Louis Acad. Sci., Vol. II, p. 98, 1862), but our 

 shell differs in having fewer and more distant costse, there being 

 generally about four of them in a space equalling the transverse 

 diameter, while O. Chester ensis has eight in the same space. 

 [Meek and Worthen, 1866]." 



Horizon and locality. — Maxville limestone. 

 Shale-nodular zone : Kroft Bridge, White Cottage. 



*5 



