18 PALAEONTOLOGY. 



of the New York form. Our specimens are scarcely one-half as large as 

 Vanuxem's figure ; but we are not sure that they are entire. The shell, how- 

 ever, certainly agrees very closely with 0. complanata in proportions and 

 the exceedingly narrow character of its volutions. Still, as it seems to 

 have nearly the same number of whorls in less than half the diameter of 

 0. complanata, it may be a distinct smaller species. If so, it may be called 

 0. nana. 



Locality^ and position. — Ute Peak, south of Muddy Creek, a tributary of 

 Bear River, Utah ; from a gray, granular limestone of Lower Silurian age, 

 and probably belonging to the epoch of the Calciferous Group of the New 

 York series. 



Genus EAPHISTOMA, Hall. 

 Eaphistoma ? EOTULiFORMis, Meek. 



Plate 1, figs. 2, 2 «, 2 h. 



Euomphalus [Raplmtoma f) rotuUformis, Meek (1870), Proceed. Acad. Nat. Sci. Philad., 

 61; and (1872) Haydeu's Ann. Eep. Geol. Survey of the Territories, 464. 



Shell small, sublenticular, or more than twice and a half as wide as 

 high, with the periphery sharply angular, and the much-depressed spire a 

 little more prominent than the convexity of the last turn below the angular 

 periphery ; umbilicus very wide, deep, and depressed-conical ; volutions 

 six or seven, exceedingly narrow, and increasing very gradually in size, all 

 obliquely flattened, or sometimes slightly concave on the upper slope, 

 which is nearly coincident with that of the spire, and with the under side 

 sloping downward and inward (being nearly one-third wider than the upper 

 surface) to the umbilicus, around which they are rather distinctly angular ; 

 aperture obliquely-rhombic. Surface unknown. 



Breadth, 0.32 inch ; height, 0.12 inch ; breadth of last turn on the 

 upper slope, ().15 inch; on the under slope, 0.18 inch; breadth of aperture, 

 0.09 inch ; height of aperture, 0.07 inch. 



This species is evidently nearly allied to Euomphalus polygyratus, 

 Roemer, from the Lower Silurian rocks of San Saba, Texas (see Kreid. 

 von Texas, tab. xi, figs. 4 a, h). It differs, however, in being much smaller, 

 its greatest diameter being less tlian one-fourth that of Eoemer's species, 



