SHUMARD — NEW FOSSILS. 



105 



access to any specimens of it, According to Dr. Owen, its 

 position is in the greenish sandstones (Potsdam Sandstone) 

 about two hundred feet below the base of the Lower Magne- 

 sian Limestone of the Northwest. 



CONOCEPHALITES MINOR, n. Sp. 



Very small ; glabella well denned by linear dorsal furrows, 

 subcircular, much elevated above the cheeks, regularly con- 

 vex, slightly longer than wide, marked on either side with 

 two short, deep,"lateral furrows, which are directed obliquely 

 backwards and reach not quite one third the distance across; 

 neck furrow linear, distinctly but not deeply impressed, sinu- 

 ate, arched forward in the middle ; neck segment short trian- 

 gular, gently convex, not elevated, posterior angle terminating 

 in a delicate acicular spine, which is prolonged backwards, its 

 length unknown ; front margin narrow, convex ; cheeks 

 rounded, having very delicate ocular ridges, which pass from 

 the eyes in a short curve to reach the glabella, a short dis- 

 tance in advance of the anterior glabellar furrow. 



Length of head, 0.10 of an inch ; length of glabella, 0.08. 



The glabella of this species has the form and convexity of 

 C. {Mmocephalus) globosus of Billings; but the latter is des- 

 titute of lateral furrows, and the neck segment is not trian- 

 gular as in our species. 



Geol. Pos. & Loc— This minute species occurs in the Pots- 

 dam Sandstone of the Bluffs of the Mississippi, near the con- 

 fluence of Black river, Wisconsin, where it is associated with 

 Obolella, Pugiunculus, and Conoceplialites Chippewaensis 

 (Owen sp.) 



Agnostus orion (1), Billings. 



A careful examination of some slabs of sandstone from the 

 Mississippi, opposite the mouth of Black river, has disclosed 

 the existence of a minute species of Agnostics, which appears 

 to be identical or at least very nearly related to the above 

 species. The specimen is a cast in friable sandstone, and is 

 the only example known to me of a species of this genus from 

 the Potsdam Sandstone of the Northwest. 



GASTEROPODA. 



Straparollus valvataformis, n. sp. 



Shell small, spire forming about one third the total height; 

 whorls about four, flattened at the summit, angulated at up- 

 per external margin, with a shallow groove just within; sides 

 flattened convex, under surface rounded; body whorl enlarg- 

 ing rapidly, bearing on its side three moderately prominent, 



