I 



The Fauna of the Magnesian Series. 97 



concave septa for nearly one and one-half volutions on the largest specimen 

 found. 



From the Oneota dolomite near Dresbach, Winona county, and near 

 Red Wing, Goodhue county, Minnesota, and at Blanchardville, La Fayette 

 county, Wisconsin. 



Helicotoma (?) peccatonica n. sp. 

 Plate V, figures 1 and 2. 



Known casts of the shell are of about three volutions. These are 

 strong and evenly convex on the inner and lower surface, while the outer 

 surface is flattened and is bounded above and below by angular carinae, of 

 which the upper may prove to be of the nature of a band. The upper sur- 

 face of each volution is divided into an outer concave surface, a convex me- 

 dian ridge and an inner flattened slope that joins the suture, and each volu- 

 tion is impressed on the upper inner side by the preceding one. 



The coil is turbinate with an apical angle of about 130°, with a wide 

 umbilicus and deep sutures. The aperture is circular in general outline. 

 The growth lines are not distinctly preserved. 



From the Shakopee dolomite in the Peccatonica river valley, near Ar- 

 gyle, Wisconsin. 



Holopea obesa Whitfield. 

 Plate V, figure 19. 



Holopea obesa Whitfield, Geology of Wisconsin, vol. iv, p. 348, pi. 

 XXVII, fig.ll, 1882. 



Shell large, of five strongly convex volutions, and with an apical angle 

 of 90° or less. Each volution is indented by the preceding one, but other- 

 wise the upper surface is strongly convex. The lower portion of each volu- 

 tion is rounded, whilethe outer surface is less and the umbilical surface still 

 less convex. The sutures are deep. No surface marks or growth lines are 

 visible oo the quartz casts that have been found. 



Found among fossils from the upper portion of Oneota formation at 

 Dresbach and Altura, Minnesota, and Blanchardville, Wisconsin. 



Metoptoma barabuensis Whitf. 



Metoptoma barabuensis Whitf,, Geology of Wisconsin, vol. iv, p. 195, 

 pi. III. figs. 16 and 17. 



One specimen, a little smaller but otherwise not distinguishable from 

 this species as figured and described, comes from the Jordan sandstone at 

 Osceola, Wisconsin, where it is associated with Pleurotomaria sweetii, 

 Whitf., etci 



Murchisonia argylensis n. sp. 



Plate V, figures 11 and 12 



Shell of many volutions (about fifteen), closely coiled ; apical angle 

 160°. The columella is slender and imperforate, the sutures deep and the 



