THE NATURAL HISTORY SURVEY. 229 



otherwise similar to the rest of the family. The foot is very 

 long and narrow, almost, or quite, equaling the shell in length. 

 Jaw: Of the usual form, wide and slightly bent. The 

 ends are blunt. Surface without ribs but vertically striated. 



Radula formula: ^T+l+i+l+s-T ('5 r ~ r S); some 

 membranes seem to have the following formula: ^-y+f+i-f- 

 |-j-j 7 (l4 1^14). The centrals are narrow, the laterals very 

 wide, while the marginals are, as usual, low and wide with one 

 large inner cusp, and several (2-6) small outer cusps, which are 

 rather blunt. 



Genitalia : Unknown. 



Distribution: "Province of Ontario, Canada to Florida and 

 west to Minnesota, Texas and Arizona." (Pilsbry.) 



Geological distribution: Pleistocene; Loess. 



Habitat: Found generally in open pastures or on the edge 

 of woods, under stones, on blades of grass and about old wood. 

 Seldom found in woods. 



Remarks: A species at once distinguished by its turreted, 

 fusiform shell and unarmed aperture. It is a rather common 

 mollusk and is widely distributed in the northern and western 

 regions. 



GENUS BIFIDARIA Sterki.* 



Bifidaria STERKI, The Nautilus, Vol. VII, p. 99, 1892. 

 "Shell: Cylindrical, turriculated, conical or oval; color 

 varying from whitish to chestnut; surface smooth and polished 

 or finely striate; sometimes lightly ribbed; aperture dentate, 

 the parietal tooth being generally large and bifid or bifurcate; 

 two (superior and inferior) palatal plicag always present, gen- 

 erally deep-seated; a tooth is generally found at the base; ad- 

 ditional denticles may sometimes be found, one on the parie- 

 tal wall, between the parietal tooth and the columella, one 

 above the upper palatal and one between the two palatals; 

 columella somewhat complex." (Sterki.) 



SECTION PRIVATULA Sterki. 



"Shell cylindric; lamellae few or none." (Sterki.) 

 89. Bifidaria corticaria Say, pi. xxx, fig. 10. 



Odostomia corticaria SAY, Nich. Encycl., Vol. IV.pl. iv, fig. 5, 1817. 



First edition. 

 Pupa corticaria SAY, Nich. Encycl., Vol. IV, pi. iv, fig. 5, 1819. Third 



edition. 

 *See The Nautilus, Vol. VI, p 2, 1892, for a list of the North American Pupidae. 



