98 The Fauna of the Magnesian Series. 



outer surface of each coil flattened. Casts ofthe interior are more uniformly 

 convex and end acutely about one-fourth the distance from the apex. 



The aperture is vertically sub-qnadrate, and there are indications that 

 it was deeply notched on the outer margin. Along the coil there appear 

 two minute longitudinal grooves, dividing the outer surface into three 

 nearly equal areas, the middle one of which is probably the band. 



Figure 11, plate V, is a sketch of a specimen showing the cavity left by 

 a shell, the apical third being entirely empty, the middle portion enclosing a 

 cast of the interior, and the lower volutions containing the replaced shell, 

 which is broken open and shows the columella. 



From near Argyle, Wisconsia, in the Shakopee dolomite. Found also 

 at Shakopee and Cannon Falls, Minnesota, in the Shakopee dolomite. 



Murcbisonia putilla n. sp. 



Plate V, figures 5 and 6. 



The specimens of this species are small turreted coils of six to eight or 

 more volutions with an apical angle of 4-5°. The outer surfabe is marked 

 by a strong angular carina a little below the middleheightof each volution, 

 and a second and third subangular carinia divide the outer from the upper and 

 lower surfaces respectively. The lower surface of the body whorl is mod- 

 erately convex and is joined with the inner surface somewhat abruptly. 

 There is a large perforated columella formed by the vertical, moderately con- 

 vex inner side ofthe volutions. The upper side of each volution coincides in 

 form w^ith the base ofthe preceding one, so that the suture is close, and in 

 fact it is formed by the contact of two carince. 



Previous to fossilization or silicification several of the specimens have 

 been indented deeply by the sharp crushing processes of some animal. These 

 wounds, besides being peculiar tooth marks in appearance, seem to show 

 distinctU' from their form and from the compression of the shells that the 

 latter yielded by bending or folding and not by fracture. One shell had 

 been also partlj'' uncoiled. 



Found in the top of the Oneota dolomite near Dresbach, Winona 

 county, and at Stillwater, Minnesota, and Blanchardville, Wisconsin. Also 

 from the Jordan sandstone near Rapidan, Blue Earth county, Minnesota. 



Ophileta alturensis n. sp. 

 Plate V, figures 3 and 4. 



Shell a dextral coil of six or more slowly expanding volutions, the spire 

 of which does not rise above the carina ofthe body whorl. The volutions 

 are strongly convex below, but are flat or concave in the umbilicus, and 

 straightened or slightly' concave below the carina on the outer side. This 

 high, acute carina on the upper outer angle gives a concave upper surface, 

 which, however, curved down to the suture on the inner side. The umbil- 

 icus is very wide. 



The growth lines are coarse and indistinct. They curve obliquely back 

 from the sutures to the carina for a distanceequal to the width of theupper 



