146 THE CHICAGO ACADEMY OF SCIENCES. 



of the base of attachment, the side cusps short; lateral teeth 

 similar to the central tooth, but bifid, the inner cusp long and 

 wide; marginal teeth at first resembling laterals, but the inner 

 cusp soon lengthens, becomes bifid, and assumes the usual 

 form of marginal. 



Genitalia: "The penis sac is long, cylindrical, receiving 



the vas deferens and retractor muscle at its summit; genital 



bladder small, globular, with a long duct, which is narrow 



above but below its middle gradually enlarges to greater than 



the width of the bladder." (W. G. Binney.) 



Distribution: Southern New York to Michigan, Canada to 

 North Carolina, Alabama and Kentucky. (Pilsbry.) 



Geological distribution: Pleistocene; Loess. 



Habitat: In open woodlands in the vicinity of water, under 

 and about logs, and debris of various kinds. 



Remarks: A species distinguished from inflecta by its open 

 umbilicus and larger size. It is quite rare, and has thus far 

 been found only in the southern region, and the specimens are 

 rather small. The shell is carried at a slight angle during pro- 

 gression, which is rather slow. 

 53. Polygyra fraudulenta Pilsbry, pi. xxx, fig. 7. 



Helix fallax W. G. BINNEY. (non Say.) Man. Amer. Land Shells, p. 292. 

 Polygyra fraudulenta PILSBRY, Proc. Phil. Acad. Sci., p. 20, 1894. 



Shell: Differing from tridentata in having "a compact shell 

 of a reddish-brown color (varying to white in some localities); 

 the spire is low-convex, composed of six closely coiled whorls, 

 the last being notably deflexed in front and strongly con- 

 stricted behind the lip. The aperture is strongly "dished" or 

 basin-shaped; the outer lip bears a broad tongue-shaped in- 

 flected tooth, situated at the position of the periphery of the 

 shell. The middle part of the basal lip bears a small squarish 

 tubercle, which is often laterally compressed. The parietal 

 wall bears an elevated oblique blade which is typically almost 

 straight and never much curved." (Pilsbry.) (Fig. 16, B.) 

 Greater diatn., 15.00; lesser, 13.50; height, 8.50; umbilicus, 3.50 mill. (8448.) 

 " 15.00; " 13.00; " 8.50; " 3.50 " (8455.) 



Animal: As in tridentata, but generally a little darker. 



Jaw: As usual, with twelve- ribs. Binney gives fourteen 

 ribs. 



Radula formula:* y -f-f + Y +i+V+l + ( 27 127). 



*This radula is from a Southern Illinois specimen. See The Nautilus, Vol. XL, p, 30, 



