98 LIMNZA. 
14. LIMNAA HAYDENI, Lea. 
Plate 17, fig. 6. 
Shell ovate-conic, smooth, thin, light horn- 
colored, imperforate; spire rather short; 
whorls five, convex; sutures deeply impressed; 
aperture ovate ; columella strongly plicate. 
Length 25, diam. 12 mill. 
Yellowstone and Big Sioux Rivers. 
The whorls are more rounded and the shell 
more cylindrical than L. palustris. 
14. A. LIMNAA SHURTLEFFII, Tryon. 
Plate 17, figs. 7, 8. 
Ovate-cylindrical, rather thin, diaphanous, 
minutely concentrically striate; spire mode- 
rately elevated, apex acute, suture impressed ; 
whorls six, flatly convex, the last one three- 
fourths the length of the shell, subcylindrical, 
compressed on the sides; aperture one-half 
(72) 
