LITHASIA. 31 



four-banded; spire short, decollate; sutures irregularly impressed; 

 whorls flattened, the last very large; aperture large, rhomboidal, 

 whitish within and much banded ; outer lip acute ; columella thickened, 

 white, incurved. 



Operculum ovate, thin, light brown, with the polar point on the 

 inner edge near to the base. 



Habitat. — Coosa and Cahawba Rivers, Alabama; E. R. Showalter. 



Diameter, -40; length, -88 ? of an incli. 



Observations. — This is a beautifully banded species, which is so 



near to brevis (nobis) in size and outline that I considered it at first as 



a strongly marked variety of that species. From examina- 



Fig 70. 

 tion now of about a dozen specimens before me, sent by 



Dr. Showalter and Dr. Lewis, I am perfectly satisfied that 



this is a distinct species. All the specimens I have seen 



have four well expressed dark brown bands, which are 



strongly exhibited within. All the specimens are so much 



worn at the apex that it is impossible to say how many 



whorls they naturally have. There is a great difference in the form 



of the apertures of the specimens before me, — some have quite an 



angular base, while others are rounded almost like a Melania. The 



aperture is probably two-thirds the length of the shell. — Lea. 



7. Ii. Showalterii, Lea. 



Lithasia Showalterii Lea, Proc, Acad. Nat. Sci., p. 18S, 1850. Jour. Acad. Nat. 



Sci.. V. i)t. 3. 1). 2i;-2, t. y5, C. 72. Obs. ix, p. 84. 

 Melania Showalterii, Lea, REEVE, Mouog., sp. 423. Beot, List, p. 33. 



Description. — Shell smooth, ovately cylindrical, rather thick, yellow- 

 ish liorn-color, banded; spire obtusely conical; sutures very 

 Fig. 71. 



much impressed; whorls six, the last large and flattened; 



aperture large, subovatc, elongate, whitish within, dark- 

 banded, obtusely angular at the base, columella thickened 

 above and below, incurved; outer lip acute and somewhat 

 constricted. 



Biafftifaf.-^ Cahawba River, at Centreville, Alabama; E. R. Showalter. 

 Diameter, -38; length, -70 of an inch. 



Observations. — This species presents a number of varieties, but the 

 character of the flattened enlarged side, frequently producing quite a 

 large shoulder, is generally preserved. Sixteen out of nineteen spec- 

 imens before me have very much the same character of bauds, viz. : 



