8 2o NORTH AMERICAN INDEX FOSSILS. 



691. P. leidyi Meek and Hay den. (Fig. 1206, w, x.) Oligocenic. 

 Stout and thick with much embracing whorls, small umbilicus 



and flat spire. 



White River group of Dakota. 



692. P. lunatus Conrad. (Fig. 1206, y, z.) Miocenic? 

 Similar to P. leidyi, but more nearly symmetrical in plane of 



coiling. 



Miocenic(?) of Oregon. 



693. P. conanti Dall. (Fig. 1207, a, b.) Pliocenic. 



Fig. 1207. a, b (left and upper middle), P lanor bis conanti ; c, d (right and lower 

 middle), Planorbis disstoni, X I -3- (After Dall.) 



Spire sunken ; whorls embracing to moderate extent, upper sur- 

 face with angulation below the suture; height and width of aper- 

 ture nearly the same. 



Caloosahatchie marls of Florida, especially in Planorbis bed. 



694. P. disstoni Dall. (Fig. 1207, c, d.) Pliocenic. 

 Angulation more distant from suture and more pronounced; 



shell proportionally higher, aperture higher than wide. 

 Caloosahatchie marls of Florida. 



Family Pupam: Gray. 

 CCXV. Pupa Lamarck. 

 Cylindrical, generally narrowing towards both ends, with suture 

 scarcely depressed and with semicircular aperture which is com- 

 monly constricted by teeth on columella and on the inner and outer 

 lip. Carbonic-Recent. 



695. P. vermilionensis Bradley. (Fig. 1208, f,g.) Carbonic. 

 Few rounded, gradually enlarging whorls, with deep sutures; 



aperture with one basal and one strong columellar tooth. 

 Coal measures of Indiana. 



